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ELEMENTS OF CHEMISTRY 



A WORK FOB USE IN 



HIGH SCHOOLS, ACADEMIES, AND 
MEDICAL COLLEGES 



BY 

S. P. MEADS 



FIFTH EDITION 



EIGHTEENTH THOUSAND 





1 1/1/ 



/I 



?c^ 



SILVEE, BUBDETT & CO., PUBLISHEBS 
Xeav York BOSTON Chicago 



\ 












Copyright, 1885, 
By S. P. MEADS. 



Copyright, 1891, 
By SILVER, BURDETT & CO. 






Preface to Second Edition. 

. ^ ■ 

^HPHIS Primer has been prepared for use especially in those schools 
(UJ) ^xt can »^ ve *° chemistry only one term's work. It has grown 
c^& out of the needs of the class-room, as I have felt them. Its 
statements are necessarily somewhat narrow, confining the pupil to gen- 
eral rules. Refined accuracy means a treatise, not a primer. I have 
given in the following pages as much as I think the average class can 
digest in a single term, and I hope my fellow-teachers will carefully 
examine the plan throughout before passing judgment. 

I have freely consulted whatever chemical works were within my 
reach, especially Attfield, Barker, Roscoe and Schorlemmer, Eliot and 
Storer, Appleton, and Jones. 

For criticisms and valuable suggestions in preparing this Second Edi- 
tion, I am indebted to Prof. Joseph LeConte and Prof. W. B. Rising, 
of the University of California. I wish to acknowledge my obligation 
to many teachers who are using my humble work in their classes, es- 
pecially to Prof. Geo. R. Kleeberger, of the State Xormal School, San 
Jose, and to Mr. Volney Rattan, of the Girls' High School, San Fran- 
cisco. Nor should I forget my indebtedness to Mr. C. B. Bradley in 
the preparation of my First Edition. 

An experience of three years in teaching chemistry to medical stu- 
dents has enabled me, I hope, to anticipate their wants in several direc- 
tions. It has shown me how greatly they need an elementary book 
before opening the excellent but voluminous works which should be 
their life companions. 

Natural Science Dept., S. P. Meads. 

Oakland High School, Jan. 2, I884. 



Preface to Fifth Edition, 



TiTCTIXG upon the advice of many teachers who have used my 
rM book since its first appearance, I have changed the name in this 
edition from Chemical Primer to Elements of Chemistry. 
I have also availed myself of suggestions, and have improved the body 
of the work in several respects. I have enlarged the Appendix, that 
the book may furnish material for a second term's work. I have kept 
in mind, not those few high-school teachers who are teaching chem- 
istry with sufficient knowledge and thoroughness to meet the require- 
ments of a college course, but rather those teachers who, though 
well aware that they are coming short of an ideal standard, yet are 
conscientiously desirous of doing the best they can with limited time 
and limited facilities. The good words which come to me occasion- 
ally from these last fellow-laborers of mine have been a great source 
of pleasure to me. 

S. P. Meads. 
Oakland, California, April 16, 1891. 



BRIEF SUGGESTIONS -MIXED. 

FOR SMALL SCHOOLS AND INEXPERIENCED TEACHERS. 



S\0 not allow pupils lazily to pronounce the symbol or the formula 
it/ instead of the name ; i. e., wherever "H" occurs, see that it is 
called hydrogen. . . . Have the pupils copy the two Reference Tables 
(pp. 16, 29 ; see Note 2, p. 18), and allow them the free use of these for 
the entire term. Never compel them to memorize formulas, atomic 
weights, strength, etc. It is as important to know what not to remem- 
ber, as to know what should be remembered, since the former com- 
prises by far the larger portion of any text-book. . . . Let the pupils 
perform all experiments (except, perhaps, a few difficult ones, or for 
the sake of taking your turn with the class) in presence of the class, 
explaining each experiment as it proceeds. It takes time, but it is the 
only way to teach chemistry where a table for each student cannot be 
provided. If you haven't time, omit half the experiments to accom- 
plish this result. ... If possible secure tables, so that all pupils may 
simultaneously perform each experiment. . . . Every experiment 
teaches something, and the sooner you can impress this fact the better. 
While you should make every experiment as impressive as it can be 
made, get the pupils through the babyhood, which craves noisy or 
showy experiments, as early in the term as possible. . . . See that a 
number of larger works upon chemistry are at your desk for reference. 
. . . After you have passed the "Reactions," encourage any pupils 
who may show a special liking for the science to work out after school 
hours a number of solutions (not too complex) and dry solids by the 
Charts (p. 161 to end). . . . Teach pupils to use small flasks (test- 
tubes answer well) and small quantities of chemicals. It isn't neces- 
sary to burn a forest to prove that hydrocarbons are combustible, nor 
to blow up a continent to prove a substance explosive. . . . Do not 
be afraid to teach anything contrary to the text, if you have good 
authority for it; but let disputed points alone. Teach any simple 
principles beyond the text, instead of others more complex omitted ; 
but do not teach intricate matter outside of text, else the result will be 
pupils will know neither the text nor the "intricate matter." . . . 
Remember that one of the chief ends of a small text-book in science is 
to teach the pupil to read intelligently larger works. . . . Spend at 
least half the time in reaching carbon, p. 63. . . . Use the metric 
system throughout ; it is the system. . . . Use either thermometer. 
The Centigrade (C) is used in this book, though the corresponding 
Fahrenheit (F) degrees are given in a few places. 



INDEX. 



Acid, Acetic 121, 132 

Benzoic 133 

Boracic 85 

Carbolic 121, 137 

Carbonic 66, 159 

Citric .124 

Gallic 124 

Hydrochloric 75 

Lactic 160 

Malic 124 

Muriatic 75 

Nitric 59, 60 

Oleic 16, 130 

Oxalic 124 

Palmitic 16 

Picric 147 

Prussic 58, 78 

Salts ...140 

Stearic 16, 130 

Sulphuric 81 

Tannic 124, 125 

Tartaric 124 

Acids 25, 135 

Aconite 127, 136, 158 

Air ....34,47, 58, 67 

Albumen 122, 134, 156 

Alcohol 119, 120 

Alkalies 25, 136 

Alkaloids 125, 127, 136, 157 

Alloys 91, 143 

Alum 148, 154 

Aluminum 105, 106, 154 

Amalgam 91 

Amber 133 



PAGE. 

Ammonium 61, 62, 114 

Ammonia 60, 61, 62 

" Type 125, 126 

Anaesthetic 59, 120, 121 

Analytical Charts 162, 163 

Aniline 126, 147 

Antidotes 133 

Antimony 91, 152 

Antiseptic. . . .81, 97, 111, 112, 121 

Aqua-f ortis 60 

Aqua-regia .60, 75, 152 

Arsenicum 88, 135, 152 

Atomic Theory 10, etc. 

Atmosphere 34, 47, 58, 67 

Atoms 10-13, etc. 

Atropia 127, 158 

Balsams 133 

Barium 109, 155 

Bases 25, 136 

Basic Salts 141 

Beer. 119 

Belladonna 127, 158 

Benzol 70, 121 

Bessemer's Process 102 

Binary Compounds 11, 17 

Bismuth 104 

Bleaching 74, 81 

" Powder 74 

Blowpipe 53, 71, 94, 162 

Borax 85 

Boron 85 

Brass 143 

Bread-making 122 



INDEX. 



PAGE. 

Brimstone See Sulphur. 

Bromine 76 

Bronze 143 

Bunsen's Burner 70 

Calcium 107 

" Light 108, 154 

Calomel 97 

Camphor 133 

' Candles 69, 130 

Caoutchouc 133 

Carat 93 

Caramel 117 

Carbon 63 

Carbon Dioxide 66, 159 

Carmine 148 

Cast-iron 101 

Cellulose 116 

Chalk 108, 135 

Charcoal 63 

Chemical Affinity. . .16, 63, 76, 77 

" Cooking 122 

" Cleaning 131 

Chlorine 72, 150 

Chloroform 120 

Chloral 121 

" Hydrate 121 

Choke-damp 68 

Chromium 92 

Cinnabar . . . . 96 

Clay 87, 106 

Coal Gas 70 

Cobalt 104 

Cochineal 148 

Coin 143 

Coke 63, 70 

Collodion 116 

Compound Ethers 120 

Radical 18 

Combustion 34, 48, 49 

Copper 100, 134, 154 



PAGE. 

Corrosive Sublimate 97 

Cotton 116 

Cream of Tartar 124 

Creosote : 121 

Crystallization 5G, 145, 146 

Cupellation 95 

Cyanogen 78 

Davy's Safety Lamp 71 

Deliquesence 56 

Dextrin 116 

Dextrose 117 

Dialysis 158 

Diamond 63 

Diastase 118 

Diffusion of Gases 52, 58 

Disinfectant 50, 64, 73, 121 

Distillation 57, 119, 120 

Dyeing .... 147 

Effloresexce 56 

Elements 16 

Essences , 120, 132 

Etchings 60, 77 

Ether 120 

Ethyl Hydrate 119 

" Oxide 120 

Fats 128 

Fermentation 118, 130 

Fireworks Ill, 155 

Flame 69 

Fluorine 77 

Formula, Empirical. . . 115 

" Rational 115 

Fusil Oil 120 

Fusible Metal 104 

Galexa 98 

Galvanized Iron. 103 

Gas, Illuminating 70 

Gelatin 122, 125 

German Silver 143 



INDEX. 



Glass S6, S7 

Glue 122 

Gluten 1-2-2 

Glycerin 130 

Gold 9-2, 153 

Graphite 63 

Gum Arabic 116 

Gum Resin 133 

Gun Cotton 116 

Gunpowder Ill 

Gutta-percha 133 

Gypsum 10S 

Halogexs 27, 72 

Hard Solder 143 

" Water 54 

Hematite 23, 101 

Hydrocarbons 48 

Hydrogen 50, 149 

Hydrogen Sulphide 82, 162 

India-Rubber 133 

Indigo 147 

Ink 73, 125, 132 

" Printers' 73 

Iodine 76 

Iron 101 

Isomerism 115 

Lake 148 

Laudanum 127, 136 

Laughing-gas . . 59 

Lead 98, 103 

Leather 125 

Lime 107 

Lime-light 154 

Linen 116 

Litmus 25 

Litharge 65 

Logwood 148 

Lunar Caustic 95 

Lye 129, 136 



PAGE. 

Madder 148 

Magnesium 34, 106 

Malt 119 

Manganese 105 

Marble 10S 

Marsh-gas 70 

Matches 83 

Mercury 96, 153 

Metals 92 

Methyl Alcohol 120 

Metric System 160 

Milk 122, 134 

Miscellaneous Questions, 45, 7S, 138 

Molasses 117 

Mordant 148 

Morphine 127, 136, 157 

Mortar .108 

Xaptha 110, 112 

Xascent State 63 

Xickel , 104 

Xicotine 127 

Nitre Ill 

Xitrous Oxide 59 

Xitrogen 57 

^Nomenclature 17, 24 

Oils 128 

Olein 128 

Opium 127, 136, 157 

Organic Acids 124 

" Bases 127, 157 

" Chemistry 114 

Oxides 34 

Oxygen 46, .149 

Ozone 50 

Paper 116 

Paregoric 127 

Pearlash Ill 

Pencils 63 

Petrifaction 86 

Pewter 143 



8 



INDEX. 



PAGE. 

Phosphoresence 84 

Phosphorus 83, 137, 151, 152 

Photography 95, 96, 153 

Plants, Office of 67 

Plaster of Paris 108 

Platinum 94, 149 

Plumbago 63 

Porcelain 87 

Potash 110 

Potassium 110 

Quartz 86,93 

Quicksilver 96 

Quinine .127, 157 

Reactions 33 

Reference Table 1 16 

Table II 29 

Table II. — (con.). . .160 

Resin 133 

Rochelle Salt 141 

Rosin .... 133 

Sago 116 

Sal-ammoniac 60, 114 

Saleratus ... Ill 

Salt, Common 112 

Salts 25 

Salts, acid, etc 140 

Salts, Epsom 106, 135 

Salts, Glauber's 113 

Salts, Rochelle 141 

Saltpetre Ill 

Sand 86 

Selen-salts 142 

Shellac 133, 155, 158 

Shot 143 

Silicon 85 

Silver 94, 153 

Soap ...128,131 

Sodium 112 

Solder 143 



Solution 37 

Spectrum Analysis 143, 144 

Stalactites 108 

Starch 115, 122 

Stearin 128 

Steel.... 102 

Strontium 109 

Strychnine 127, 136, 157 

Sublimation 8Q 

Subnitrate of Bismuth 142 

Sugar, Cane 116 

" Grape 117, 155 

" of Lead 99 

Sulphur 79 

Sulph-Salts 142 

Tapioca 116 

Tar 70 

Tartar Emetic 91, 124 

Tin 103 

Turpentine 133 

Type-metal 143 

YehdigPvIS ... 100 

Vermilion . . . . ... 96 

Ventilation 68 

Vinegar 121, 136 

Vitriol, Blue ....100 

" Green 102 

" Oil of : .... 81 

Volatile Oils 132 

Water 13, 14, 37, 53, 139 

" of Crystallization 55 

" type 26, 125 

White-lead 99 

Wines 119 

Woody Fiber .116 

Yeast 118, 123 

Zinc 103 



THEORETICAL CHEMISTRY, 



CHAPTER I. 



INTRODUCTION. 



Matter exists in three states: — 

1. Solid: Ex., iron, lead, ice. 

2. Liquid: Ex., mercury, bromine, water. 

3. Gaseous: Ex., hydrogen, air, steam. 

Nearly all substances ordinarily in the solid state may, by applying 
heat (and removing pressure), be made first liquid and then gaseous. 
Nearly all gases, by cold and -pressure, may be made first liquid and then 
solid 

A change which merely converts a solid to a liquid, or a liquid to a 
gas, or vice versa, however wonderful such change may be, is not a 
chemical, but a physical change. Ex., Ice may be heated and converted 
into water, a liquid, and then into steam, a gas. 

All such changes are studied in Phy4cs, not in Chemistry. Chemistry 
deals with such changes only incidentally. 

The molecules (small, invisible particles) of a solid move with diffi- 
culty upon each other The molecules of a liquid move readily upon 
each other, so that the liquid assumes the shape of the vessel holding it. 
The molecules of gas have an apparent repulsion for each other, so that 
a gas, regardless of its specific gravity (i. e. whether light or heavy), 
escapes from an open vessel and diffuses itself throughout the surround- 
ing space. 

We learn many things incidentally about solids and liquids before 
studying either Physics or Chemistry. We know comparatively little 
about gases, except about the gaseous ocean of air at the bottom of 
which we live. To the chemist, however, the gas is in many respects 
the simplest state of matter and the most convenient for him to exam- 
ine critically. 



10 CHEMICAL PRIMER. 



CHAPTER II. 



The Atomic Theory divides matter into: — 

1. Mass. — Any portion of matter appreciable by the 

senses. 

2. Molecule. — The smallest particle of matter that 
can take part in a mere physical change. It may exist 
alone. 

3. Atom. — The smallest particle of matter that can 
take part in a chemical change. An atom does not exist 
alone. Atoms compose molecules : i. e., two or more atoms 
make a molecule. 

Chemistry treats of the atomic condition of matter 
and especially of atomic changes. 

It will be inferred from the definitions that a mass may be very large 
or exceedingly small, also, that the molecule and the atom are not visi- 
ble even with the aid of the most powerful microscope, otherwise they 
would be "appreciable by the senses." 

Chemistry treats of more subtle changes than physics. If the mol- 
ecule is not broken up and the atoms set free to form new combinations, 
it matters not how violent, or how wonderful the change may be, it is 
purely 'physical and in no sense chemical. 

Of course, atoms "exist alone" during the instant of chemical change. 
One atom may rarely make a molecule. At this stage, however, the 
pupil should not trouble himself with exceptions. 

Note. — We know that there are masses and molecules, but we do not 
know that there is any such thing as an atom. More than this we do 
not care whether there is or not. The atom is to chemistry what the x, 
oi unknown quantity, is to algebra. , It enables us to accomplish results 
which otherwise would be impossible. The Atomic Theory is as useful 
in the study of chemistry as the Arabic numerals are in the study of 
arithmetic. 



THEORETICAL CHEMISTRY. 11 



CHAPTER III. 



An Element is a substance whose molecules contain 
atoms of one kind only ; therefore it cannot be separated 
into two or more different kinds of substances. Ex., gold, 
lead, hydrogen. 

A binary compound is a substance which has two dif- 
ferent kinds of atoms in its molecule, and therefore can 
be separated into two different kinds of substances. Ex., 
water, common salt. 



A molecule of hydrogen may be represented thus | H H j in which 
each H represents an atom of hydrogen and the boundary line simply 
the fact that the two atoms are bound together by chemical bonds into 
one molecule. 

It is well to remember that we can only represent a point on the board, 
or upon paper, we cannot make one. We only represent lines, we can- 
not make them. The "point" on the board is infinitely too large for a 
real point. So the H above is too large to represent with any suggestive- 
ness as to size an atom of hydrogen. Let the pupil imagine in place of 
the two H's in the molecule two infinitesimally small particles of hy- 
drogen side by side. These are precisely alike ; are mysteriously held 
together by some peculiar law allied to gravitation, and act in most 
cases, i. e. in all physical cases, as one particle. The two atoms taken 
together (the one molecule of hydrogen) must be much too small to be 
seen even with a microscope, and there must be many millions of mol- 
ecules in a very small vessel full of hydrogen. 



A molecule of water may be represented thus | HOH | or more 
briefly, thus | H 2 | or still more briefly by omitting the boundary 
line, thus H.,0. This means that in a molecule of water there are two 
atoms of hydrogen (precisely alike) and one atom (unlike the other two) 
of oxygen. 



12 CHEMICAL PRIMER. 

Practically the representation H 2 means that two parts by volume of 
hydrogen unite with one part by volume of oxygen to form the binary 
compound which we call water. (Take this for granted now; we'll 
prove it by and by. See Water, index. ) Thus, two gases unite to 
form a liquid. But this is a chemical change, because the atoms of the 
molecules of hydrogen and of oxygen are disturbed, their molecules 
being broken up to form new molecules of a different substance, water. 
The change may be represented thus: — 



[ HH 1 1 HH 1 + [_00j = | H^T] [ H a O 

This means that two molecules of hydrogen and one molecule of oxy- 
gen break up into separate atoms and then instantaneously reunite into 
two molecules of water. 

The atomic change (beginning at the instant when the molecules are 

broken up) may be written thus: — 

H 2 + = H 2 

Two atoms One atom One molecule 

of hydrogen of oxygen of water 

Chemical changes are called Reactions. For all ordinary purposes 
the atomic reaction is correct. As it is not nearly so difficult as the 
molecular reaction (first above) it alone will be used in this book. 

There are about sixty -seven elements known, and these 
may be considered the alphabet of chemistry. From these 
all chemical compounds are formed, as words from letters. 

ATOgadr0 5 S Law that " equal volumes of all gases, having 
the same temperature and pressure, contain the same number 
of molecules" — enables us to find the relative weights of 
atoms of different elements. [Chaps. IV and V.] 

The chemists' thought of a quart of oxygen is like our thought of a 
quart of peas. The peas represent the molecules, the halves the atoms, 
the seed- coats the attractive force which holds the two atoms of the 
molecule together, and the spaces between the peas represent the inter- 
molecular spaces. A solid element is like the gas, only the intermolec- 
ular spaces are smaller. For the non-elemental substances, as water, 
you have only to increase the number of pieces (usually) within the 
seed- coats, and make some of them unlike the others. 



THEORETICAL CHEMISTRY. 13 



CHAPTER IV. 



Atoms of different elements differ in three essential 
respects : — 

1. In weight. 

2. In quality. 

3. In strength. 

The First Difference needs no explanation. When we say that 
atoms differ in weight, we mean that they differ in weight. (Atoms of 
the same element have always the same weight. ) 

The Second Difference needs explanation. The quality of meat 
may be determined by eating it, and the quality is said to be good or 
bad. The quality of cloth may be told by wearing it, and the quality of 
cloth is also said to be good or bad, as the case may be. 

The quality of an atom is determined by electricity, and the atom 
is said to be, not good or bad, but positive or negative. 

If a current of electricity from two or more of Bunsen's quart cups be 
passed through the binary compound water, the water will be decom- 
posed and bubbles of gas will appear at each pole. If the gas from the 
positive pole be collected (see Fig. No. 1) and tested, it will prove to be 
oxygen. If the gas from the negative pole be collected and tested, it 
will prove to be hydrogen and will have twice the volume of the oxygen. 

Note. — The water should be acidulated slightly with sulphuric acid. 
The hydrogen will always have a little more than twice the volume of 
the oxygen, because the liberated oxygen is more soluble in (the remain- 
ing) water than the hydrogen. The pupil may learn right here that a 
gas can be dissolved in water just as well as a solid. The nature of a mere 
solution will be explained hereafter. [See Chap. XV.] 



14 



CHEMICAL PRIMER. 




Fig. 1. A A — Platinum Ends (poles, or electrodes). 

The law of electricity being that "like electricities repel each other and 
unlike attract" — as oxygen goes to the positive pole, it is negative to 
hydrogen, and as hydrogen goes to the negative pole, it is positive to 
oxygen. 

Thus, by means of a battery acting upon their compounds, the ele- 
ments may be arranged with reference to their "quality" — but an atom 
of an element is always positive or negative, not absolutely, but rela- 
tively. 

For example, if we arrange in line sixty-seven boys from north to 
south, the first boy would be a north boy to any other. The second boy 
would be a south boy compared with the first, but a north boy compared 
with the third. The tenth boy would be a south boy compared with the 
fourth, but a north boy compared with the fifteenth. Any boy would 
be a south boy to all boys north of himself, but a north boy to all boys 
south of himself. 

Thus, the elements are arranged in line according to their "quality," 
oxygen standing first, being most negative. (See Reference Table No. 1.) 
This difference in "quality" is of the utmost importance in chemistry. 

The Third Difference may be explained by an illustration. 

If one man can hold a 100-lb. weight, we may call his strength one. 
Then, if another man can hold two 100-lb. weights, his strength would 
be two, and it would take two of the first kind of men to match one of 
the second kind. If a tliird man can hold three 100-lb. weights, his 



THEORETICAL CHEMISTRY. 15 

strength would be three, and it would take three of the first kind of men 
to match one of the third. But how shall we match the second kind 
of men and the third kind ? Evidently, three of the second kind would 
match two of the third kind. If a fourth man can hold four 100-lb. 
weights, his strength will be four ; etc. 

The strength of atoms is measured, not by 100-lb. weights, but by the 
strength of hydrogen atoms. The strength of the hydrogen atom is 
taken as one. The strength of those elements whose atoms each require 
one atom of hydrogen to match them is one ; of those elements whose 
atoms each require two atoms of hydrogen to match them, the strength 
is two ; of those whose atoms require three atoms of hydrogen, the 
strength is three, etc. 

These elements are called respectively monads (1), 
dyads (2), triads (3), tetrads (4), pentads (5), hexads (6), 
and heptads (7). This strength of the atoms is often 
expressed adjectively by the terms, univalent (1), bivalent 
(2), trivalent (3), quadrivalent (4), pentivalent (5), etc. 



CHAPTER V. 



The names of the elements are abbreviated in chemical 
language. O is the symbol for oxygen, S for sulphur, Sb 
for antimony (Latin, stibium), etc. The dictionary will 
give the Latin name from which a number of the symbols 
are derived. 

The following Reference Table exhibits the symbols of 
the most important elements and the three essential dif- 
ferences of their atoms: — 



REFERENCE TABLE NO. i. 



SYMBOL. 


QUALITY. 


ATOMIC 


f STRENGTH. 




Shown b}' order of names. 


WEIGHT. 






Negative End. 









Oxygen 


16 


2 


s 


Sulphur 


32 


*J-i U 02 


N 


Nitrogen 


14 


3 *'% 


( F 


Fluorine 


19 


i a^s 


CI 


Chlorine 


35.5 


i > § 


J Br 


Bromine 


80 - 


1 d 2 c 


I 1 


Iodine 


127 


1 o|J 


\CN 


Cyanogen* 


26 


1 © >T r o 

A © © O 


Se 


Selenium 


79 


9 2L 


P 


Phosphorus 


31 


5— (3) 


As 


Arsenicum . 


75 


3-(5) 


Or 


Chromium 


52.5 


2 


1 


B 


Boron 


11 


3 


CD 


* c 


Carbon 


12 


4-(2) 


C 


Sb 


Antimony 


122 


3-(5) 


1 


' Si 


Silicon 


28 


4 


' 


H 


HYDROGEN 


1 


1 


i 


1 Au 


Gold 


196.6 


3-(l) 


0} 


Pt 


Platinum 


197 


4-(2) 




i Hg 


Mercury 


200 


2 (Hg 2 adyad) 


i 


' Ag 


Silver 


108 


1 


Cu 


Copper 


63.5 


2 (Cn 2 a dyad) 


Bi 


Bismuth 


210 


3 


Sn 


Tin 


118 


4-(2) 


Pb 


Lead 


207 


2-(4) 


Co 


Cobalt 


59 


2 


Ni 


Nickel 


59 


2 


Fe 


Iron 


56 


2 (Fe 2 a hexad) 


Zn 


Zinc 


65 


2 


Mn 


Manganese 


55 


2-(4) 


AI 


Aluminum 


27.5 


Al 2 a hexad 


Mg 


Magnesium 


24 


2" 


Ca 


Calcium 


40 


2 


Sr 


Strontium 


87.5 


2 


Ba 


Barium 


137 


2 


(Na 


Sodium 


23 


1 


K 


Potassium 


39 


1 


Ih 4 n 


Ammonium* 

Positive End. 


18 


1 



*Not elements. (See Chap. VI.) fN/ot Chemical Affinity (see Index). 



THEORETICAL CHEMISTRY. 17 



CHAPTER VI. 



A binary compound is named by placing the positive 
element first and changing the ending of the negative into 
ide. 

EXAMPLES. 

Formula. Name. 

Na CI = sodium chloride. 
K 2 O = potassium oxide. 

It will be noticed that sodium and chlorine are both monads (see 
strength in Reference Table No. 1), and therefore it requires one atom 
of each to match the other in the molecule, as in the first example. In 
the second example, potassium is a monad (see Table), but oxygen is a 
dyad, therefore it takes two atoms of potassium to match one of oxygen 
in the molecule. 

Again, in putting dyads and triads together, we must take three dyads 
to match two triads in the molecule, a strength of two times three equal- 
ing a strength of three times two. 

EXAMPLE. 

As 2 S 3 = arsenicum sulphide. 
Again, two dyads must be taken to match one tetrad. 

EXAMPLE. 

C 2 = carbon oxide. 

Aluminum is peculiar. A single atom is never found in any molecule, 
but two atoms together have a strength of six. 

EXAMPLE. 

Al 2 Cl 6 = aluminum chloride. 
Five dyads must be taken to match two pentads. 

EXAMPLE. 

P 2 S 5 = phosphorus sulphide. 
2 



18 



CHEMICAL PRIMER. 



Note. — Just as we sometimes say "the father of Mary,''" instead of 
"Mary's father,'' the older chemists say "sulphide of phosphorus, ' : 
instead of "phosphorus sulphide." They also express the same by 
"sulphterig of phosphorus,' or "sulphuretted phosphorus." 

Atoms of two or more elements bound together by 
chemical bonds so closely as to act as one atom in the 
formation of compounds, form a Compound Radical. 

Two very important compound radicals are inserted in the Reference 
Table and linked with the elements with which they are closely allied. 
Their compounds with a single element are considered and named as 
binaries, though they contain three different kinds of atoms. 

EXAMPLES. 

K CN = potassium cyanide. 
(H^N^S = ammonium sulphide. 
H 4 N CN = ammonium cyanide. 

Note. — The pupil should write the 
formulas and names of a great many 
binary compounds, putting the atoms 
together according to the strength in the 
Reference Table. Be careful that the 
multiplications make the positives match 
in strength the negatives, as in the exam- 
ples. It does not matter if many of the 
compounds are merely theoretical. It is, 
however, a great gain at this point to 
have as many binaries as combine according 
to the first strength given in the Table, shown 
to the scholars. For instance, a substance might be shown and the 
class told that it was a compound of sulphur and sodium. They should 
then all write labels for the bottle containing it, giving formula and 
name, as in Fig. 2. Extra Reference Tables for class-room use are to 
be found at the close of this book. These may be cut out and pasted 
upon flexible cardboard. 




THEORETICAL CHEMISTRY. 19 



CHAPTER VII. 



Ic and Ous Binaries. 

These may be introduced by an illustration: In one of our Eastern 
townships lived a man who was afflicted with periodic insanity. When 
in his right mind (ordinarily), he had the strength of his brother. He 
could be called a monad. In one of his insane fits he carried three men 
upon his back over a gate five boards high. He became a very decided 
tiiad, you see. 

Now, the Reference Table No. 1 gives the "strength" of chlorine 
one, i. e. t as a monad — but sometimes it acts with a strength of three, 
i. e., as a triad (sometimes as a pentad, or even as a heptad). 

Carbon is given a strength of four, and this it ordinarily has — but 
sometimes it acts with a strength of only two. Thus, it forms two 
binary compounds, with oxygen, C0. 2 and CO. Evidently, if we say 
carbon oxide, we shall not know which is meant, because the name may 
apply to either. 

As a rule, an atom with an even strength never has an odd strength, 
also, an atom with an odd strength never has an even strength. The 
strength increases or decreases by twos. This will be noticed as we pro- 
ceed. 

The column in parenthesis in Table under Strength, includes all the 
variation that beginners will need for reference' in writing binaries. 

The above colloquial use of the suffixes ic and ous, as adjectives, 
should be confined to the class-room. 

When the positive takes more of the negative, it has 
the ending ic, when it takes less of the negative, it has 
the ending OUS. 

EXAMPLES. 

C 2 = carbonic oxide. 
CO = carbonous oxide. 



20 CHEMICAL PRIMER, 

When the positive takes more of the negative than in the ic com 
pound, it has the prefix per (from hyper = more); when it takes less of 
the negative, than in the ous compound, it takes the prefix hypo (under). 

EXAMPLES. 

Clg = hypo-chlorous oxide. (CI a monad) 

CI 2 3 — chlorows oxide. (CI a triad) 

CI 2 5 = chloric oxide. (CI a pentad) 

Cl 2 7 — per-chlori'c oxide. (CI a heptad) 

Note. — Per and hypo are rarely prefixed to the negative instead of 
to the positive. Few elements form hypo- and per binaries, and the 
pupil will be troubled very little with them. They are given here so 
that if, in the larger text-books, he sees hypo- and per- binaries men- 
tioned, he may have some idea of what is meant. 

The scholar should here solve many problems, such as the following: — 

1. Put together sulphur and antimony to form two compounds, giving 
antimony a strength in the first compound as in the Table, and in the 
second compound a strength as in the parenthesis. Name. 

Ans. Sb 2 S 3 = antimontws sulphide. 
Sb 2 S 5 = antimomc sulphide. 

2. Put together iodine and mercury, giving mercury a strength, first, 
as in Table; second, as in the parenthesis. Name. 

Ans. Hg I 2 ~ mere line iodide. 
Hg 2 1 2 = m^rcurows iodide. 

Note. — In this last compound, mercury seems to be a monad, i. e., it 
seems to change from the even to the odd strength. A few of the other 
elements do the same thing, as you will see. The single atom of mer- 
cury takes two of the negative in the first (ic) compound, and only one 
of the negative in the second (ous) compound. 

The ic and ous compounds of the same elements often differ very much 
in physical and chemical properties. You will see, by looking at the 
samples from the laboratory, that mercuric iodide is red, while mercur- 
ous iodide is green. Again, carbonic oxide is not poisonous, while car- 
bonous oxide is poisonous. 

Notice that for gold, copper, tin, lead, and iron, the adjectives (from 
Latin) aurous, cuprous, stannous, plumbous, and ferrous, respectively, 
are used in one compound, and auric, cupric, etc., in the other. 



THEORETICAL CHEMISTRY. 21 



A binary rnay be named by prefixing the Greek num- 
erals [mon, di< tri, tetra. etc). In all cases where a mis- 
take would be likely to occur, this very exact method is 
used. 

EXAMPLES. 

CO = carbon monoxide, (ous.) 
C0 2 = carbon dioxide, (ic.) 
Fe 2 3 == di-ferric trioxide. (ic.) 

Note. — The older chemists used, as a rule, ver and proto for ic and 
ous respectively, as: — 

Fe ~ protoxide of iron, instead of ferrous oxide. 
Fe 2 3 = peroxide of iron, instead of ferric oxide. 

Instead of ous, the prefix sub was also used, as: Hg 2 Cl 2 = subchlo- 
ride of mercury. 

Compounds, in which tnere were two of the positive to three of the 
negative, often took the prefix sesqai (one and one-half), as: — 
Fe 2 3 = sesquioxide of iron. 

There is still another name which the unfortunate druggist must 
learn, a Latin name with which he labels his bottles. (See Chap. XIII. , 
Note. ) 



Write the names of the following, using ic and ous in the first three 
columns and the Greek prefixes in the last column: — ■ 



As 2 3 = 


Au Cl 3 = 


Sb 2 5 = 


Mn0 2 = 


AsA = 


Fe 2 Cl 6 = 


Pt CI, = 


CO, = 


Sn S 2 = 


Hg 2 Cl 2 = 


Sb 2 S 3 = 


PC1 5 = 


SnS = 


Au CI = 


Pt Br 2 = 


p Cl 3 = 


PA = 


Cu 2 = 


CO = 


Fe 2 S 3 = 


P2O3 = 


CuO = 


FeS = 


CO = 


Hg Cl 2 = 


Hg 2 CN = 


Pb Br, = 


cs 2 = 


HgS = 


Pb I 2 = 


CuS = 


PbO = 



22 CHEMICAL PRIMER, 



CHAPTER VIII. 



Inspection of the following questions and the methods 
of solution will reveal the great value of the Atomic 
Theory to the chemist, and, indeed, to the world of 
industry. 

1. In 116 kilograms* of mercuric sulphide (Hg S) how 
much mercury? 

Hg = 200 atomic weight (see TableJ. 
S = 32 



Hg S = 232 molecular weight. 

corresponds to 

232 kgs. of Hg S = 200 kgs. of Hg. 

1 « " = ^ of 200 kgs. of Hg. 
116 " " = \\% of 200 ; < 

£Jf of 200 = 100 kgs. of Hg Ana. 

2. How much lead chloride (Pb CL) could be made 
from 50 grams of lead? 

Pb = 207 at. wt. 
CI, = 71 " 



Pb Cl 2 = 278 mol. wt. 
207 Pb = 278 Pb Cl 2 

1 " = jfa of 278 Pb CI, 
50 " = -i^r of 278 " = 67 y Vt grams. Ana. 

It will be noticed that there are two distinct kinds of questions. The 
first gives the weight of the binary and requires the weight of the 

*See metric system, Index. 



THEORETICAL CHEMISTRY 23 



element The second gives the weight of the element and requires the 
weight of the binary. In the first class of questions of course, the 
answer is less than the given weight. In the second class the answer is 
mo e than the given weight. After obtaining the molecular weight by 
the addition of the atomic weights, set in the left hand number of the 
first equation the weight (atomic or molecular) of the given quantity as in 
the example. 

3. From one metric ton of the iron ore hematite (Fe 2 3 , ferric oxide), 
how many kilograms of iron could be obtained, provided the hematite 
contained 25 per cent, of earthy impurities, or waste? 
1 M. T. == 1000 kgs. 
25 per cent, waste leaves 75 per cent. 

750 kgs. of pure ore 3 
Fe 2 — 112 at. wt. 
3 = 48 " 



Fe 2 3 = 160 mol. wt. 

160Fe 2 O 3 = 112 Fe 

1 " =Tio ofll2Fe 
750 " = ^f-g- of 112 Fe = 525 kgs. iron, Ans. 

Note. — The pupil should perform very many problems similar to the 
above. To show one common process of getting the element from the 
ore, heat some lead oxide (litharge) on charcoal (carbon) in the blow- 
pipe flame. The carbon takes the oxygen from the lead, forming car- 
bonic oxide (C 2 ) and leaves the lead free, i. e. , not combined with 
any other element (see Exp. 50). 

4. How much lead in 100 kgs. of lead oxide (Pb O)? Ans. 92|ff. 

5. One M. T. of lead would make how many kilograms of litharge ? 

Ans. 1077 2 6 or° 

6. How much silver in 50 kgs. of silver chloride? 

7. How much silver chloride must be taken to obtain from it 50 kgs. 
of silvei ? 

8. How much mercury would be required to make 150 kgs. of vermil- 
ion (mercuric sulphide)? 

9. How much lead in one metric ton of plumbous chloride ? 

10. How much gold in 500 grams of auric chloride 9 



24 CHEMICAL PRIMER. 



CHAPTER IX. 



A ternary compound is one having three different 
kinds of atoms in its molecule 5 and therefore can be sep- 
arated into three different kinds of substances. 

Most ternaries contain oxygen as a connecting element ; 
it is therefore omitted in the name. It is understood to 
be the connecting element, unless otherwise mentioned 
(see Sulph- Salts, Index). It is not omitted in the form- 
ula. 

A ternary is named by placing the positive first and 
(the O being omitted) the negative last, with the ending 
changed into ate. 

EXAMPLES. 

K CI 3 = potassium chlorate. 
H 2 SO d = hydrogen sulphate. 

As in binaries, we have different compounds of the same three ele- 
ments, and so must have different names. 

When the is less (relatively to the negative) than in the ate com- 
pound, the negative takes the ending ite. 

EXAMPLES. 

K CI 3 — potassium chlorate. 
K CI 2 = potassium chlorite. 

Rarely the may be less than in the ite compound, when hypo 

ite is used. Sometimes the is more than in the ate compound, when 
per ate is used. 

EXAMPLES. 

K CI O = potassium hypo- chlorite. 
K CI 2 = potassium chlorite. 
K CI 3 = potassium chlorate. 
K CI 4 = potassium per-chlorate, 



THEORETICAL CHEMISTRY, 25 



As in binaries, the hypo- and per- ternaries are very few and will trouble 
the student very little. The ite compounds are also few in comparison 
with the ate. This will be a good rule for beginners: "Call every ter- 
nary an ate unless you have reason to call it an ite." 

Name the following: — 

H 3 P0 4 = ? Mg S0 4 = 1 Which is the ate and 

,^ XT ~ AT on , l r which the ite com- 

KN0 3 = M g S0 3 = J pound? 

Ca 2 HO = Ca 3 2 PO, = 

Note. — Don't ask why the atoms in the above are matched or multi- 
plied as they are. You will not understand this till you have completed 
Chap. XII. 



CHAPTER X, 



There are three great classes of ternaries, with which 
the scholar should early become familiar, viz. : — acids, 
bases, and salts. 

Acids are generally sour, and turn blue vegetable colors 
(such as litmus) red. 

Bases (those that are soluble in water are called alka- 
lies) turn red litmus paper blue. 

Acids and bases are chemical opposites. They attack 
and destroy each other, forming salts (and water). This 
power of forming a salt with its opposites is the true test 
for an acid or a base. The test with litmus paper is a 
very good one and usually answers. 

Note. — The pupil should here test a number of acids and bases with 
litmus paper. Of course, acids, bases, and salts may exist in either of 
the three physical states: solid, liquid, or gaseous. Solid or gaseous 
acids and bases must be dissolved in water before testing, or the litmus 
paper wet (which is the same thing). 



26 CHEMICAL PRIMER. 



Acids, bases, and salts are said to be formed on the 
water-type, thus: — 



HHO = molecule of water. 



H, a negative element and O = a molecule of an 



acid. 



A positive element, H and O = a molecule of a 



base. 



A positive element, a negative element and O j = 



a molecule of a salt. 

In the above water-type, by a negative element is meant one negative 
to hydrogen, and by a positive element one positive to hydrogen. 

In the Reference Table, if the element is above hydrogen, it is nega- 
tive in forming acids, bases, or salts; if below hydrogen, it is positive. 

Write the name of the following, and mark as acid, base, or salt. 
(Consult Table No. 1. A large figure multiplies all atoms that follow 
it.) 

+ - 

K CI 3 = potassium chlorate = salt. 

H 2 S 4 — hydrogen sulphate = acid. 

+ 

Ca 2 HO = calcium hydrate — base. 

Na 2 SO, = ? (H, N) a S0 4 = Na HO = Ba 2 HO = 

HN0 3 = H 2 S0 3 — Mg 3 2PO, = PbCrO,^ 

KN0 3 = Ag 3 As0 4 = NaC10 3 = H 3 B0 3 = 

Note. — The division into positive and negative elements is not always 
made at hydrogen. Thus, zinc is usually positive in forming by the 

+ 

water-type, and Zn 2 HO zinc hydrate = base — but rarely, when in pres- 

+ 

ence of a stronger positive element, as potassium : Zn 2 HO zinc hydrate 
becomes (or may be considered) H 2 Zn 2 = hydrogen zincate = an 

+ - 

acid; and we have the salt K 2 Zn 2 = potassium zincate, in which Zn 
is negative not to H but to K. So chromium usually by the water-type 

acts as a negative element, and H 2 Cr 4 = hydrogen chromate = an 



THEORETICAL CHEMISTRY. 27 



acid, but rarely chromium acts as a positive element, and we have 

+ 

Cr, G HO = chromium hydrate = a base. The pupil at this stage, 
however, should not attempt to deal with exceptions, but should treat 
the rule given as though it were absolute, and should consider all elements 
above hydrogen as negative and all elements below hydrogen as positive 
in the formation of acids, bases, and salts. After deciding from the 
formula, test acids and bases by litmus paper, and thus prove the rule. 
This water type should be so thoroughly mastered that, having the Ref- 
erence Table before you, you can tell at a glance, on seeing the formula, 
whether the ternary is an acid, base, or salt. 



CHAPTER XI 



It will be noticed that in the Reference Table four neg- 
ative elements and one compound radical are linked to- 
gether. These elements are called the haloid elements 
(or halogens = salt-forming), because they form salts (and 
acids) without oxygen, i. e., they form binary salts and 
acids. 

EXAMPLES. 

H CI = hydrogen chloride = a binary acid. 

+ - 
Mg CI, = magnesium chloride = a binary salt. 

These salts and acids may be referred to the water-type by counting 

in the missing oxygen, thus H CI = hydrogen, a neg. and the missing 
O = an acid. 

"Write the name, and mark as acid, base, or salt, the following: — 

+ - 

K 2 S0 4 = potassium sulphate = salt. 

+ - 

K CX = potassium cyanide = binary salt. 
Ka., S — sodium sulphide = (neither). 

+ - 

H 4 N N0 3 = ammonium nitrate = salt, 



28 CHEMICAL PRIMER. 



HI = ? 


Ca Cl 2 = 


Mg 2 CN = 


Mg C0 3 = 


K 2 C0 3 = 


K Br = 


Ba 2 CI 3 = 


(H 4 N),C0 3 = 


H 4 N HO = 


H 3 P0 4 = 


H 2 S0 3 = 


AgCl = 


Mg, 2 P0 4 = 


Mg 2 HO = 


Mg S0 4 = 


H 4 Si 4 = 



Note. — The Na sulphide above teaches us that there are many bina- 
ries which are not to be classed as acids, bases, or salts. Only those 
binaries containing the "salt -forming" elements and radical linked in 
Table No. 1, are to be thus classified. Evidently there can be no binary 
bases. 



CHAPTER XII. 



The following Reference Table No. 2 will be found a 
great aid in writing formulas of ternaries. It is to be 
used in connection with Table No. 1, the negative 
"groupings" in No. 2, being used with the positive (to 
H) elements in No. 1, and the positive groupings (all rad- 
icals) of No. 2, with either the negative elements of No. 1, 
or the negative groupings of No. 2. The positive group- 
ings in No. 2, being radicals, unite with a single element 
to form a binary, while the negative groupings in No. 2, 
not being radicals (in the same sense), unite with a single 
element to form a ternary. 

EXAMPLE. 

(C 2 H 5 ) 2 O = ethyl oxide (common ether) = a binary; 
but 

Mg C0 3 = magnesium carbonate = a ternary; and 
K HO = potassium hydrate = a ternary. 



REFERENCE TABLE NO. 2. 



GROUPINGS. 



NEGATIVE. 




POSITIVE. 


q / HO == hydrate. 




(Radicals) 


| I N0 3 = nitrate. 


H 4 N 


= ammonium 


« J CI 3 = chlorate 


C 2 H 5 


= ethyl 


eX C a H 3 2 = acetate 


C 6 H 5 = 


= phenyl 


2 1 1 C 18 H a5 2 = stearate j 

> 1 -s C 1G H 31 2 = palmitate Win fats) 

P I ^C 18 H 33 2 = oleate J 


CH 3 = 


= methyl 


C 5 H n 


= amyl 






. / S0 4 = sulphate 






g I S0 3 = sulphite 






£ j CO3 = carbonate 






H *\ C 2 4 = oxalate 






| j C 4 H,0 6 = tartrate 






> 1 Cr 4 = chromate 






\ Se 4 = selenate 






§ / P0 4 = phosphate 


C 3 H 5 = 


= glyceryl (in fats) 


Si As 4 = arsenate 






of As O3 = arsenite 






£ 1 Sb 4 = antimonate 






^ 1 B0 3 = borate 






g \ C 6 H 5 7 = citrate. 






Quadrivalent \ Si o 4 = silicate 






Or Tetrad. ( P 2 7 = pyrophosphate 







It has probably been noticed that in the examples given in the pre- 
vious chapters, all hydrates contain HO, which acts as a monad with 
reference to the elements that go with it, also, that all sulphates con- 
tain the dyad grouping S0 4 . 



30 CHEMICAL PRIMER. 

To write the formula of any substance, whose name is 
given, as potassium carbonate, we first find the carbonate 
grouping in Table No. 2, and write it thus, C0 3 ", indicat- 
ing for convenience its strength by the two marks above. 
In Table No. 1 we find K has a strength of one; placing 
this before the carbonate grouping, we have K'CO/. But 
it takes two monads to match one dyad, therefore we must 
multiply K by two, and we have K 2 C0 3 for the formula 
required. 

Write the formula for magnesium phosphate: — 
phosphate grouping = PO/" 
magnesium = Mg"; 

As it takes three dyads to match two triads, we have 
Mg 3 2 P0 4 for the required formula. 

Note 1. — The above Table contains only the most common groupings. 
There are phosphate groupings other than the two mentioned; also other 
borate, sulphate, and silicate groupings, etc. For rarer groupings see 
''Table No. 2, continued." The number of radicals, both negative and 
positive, is countless. It is well for beginners to put a vinculum above 
the groupings and radicals until they are familiar with the method of 
matching them. 

Note 2. — H, united with the hydrate grouping, gives H HO or H 2 
= hydrogen oxide, a binary. The grouping HO is often considered a 
compound radical (hydroxyl) and its compound with an element is some- 
times named as a binary. Ex: K HO = potassium hydroxide, instead 
of as in third example above. 



THEORETICAL CHEMISTRY. 31 



CHAPTER XIII. 



Write formulas for the following, and mark as acid, base, or salt: — 

potassium arsenate = K 3 As 4 = salt. 

calcium acetate == Ca 2 C 2 Hv0 2 = salt. 

hydrogen nitrate = H N0 3 = acid. 

magnesium hydrate = Mg 2 HO = base, 
hydrogen silicate = barium phosphate = 

calcium oxalate = lead chromate 

sodium carbonate = potassium arsenate = 

calcium phosphate = ethyl hydrate (common alcoliol) = 

hydrogen acetate = ammonium oxalate = 

sodium hydrate = hydrogen tartrate = 

lead carbonate = glyceryl hydrate (glycerine) = 

magnesium phosphate = barium nitrate = 

hydrogen citrate = silver arsenite = 

Note. — Notice that in negative groupings containing three or more 
elements, the hydrogen is not counted in applying the water-type. See 
calcium acetate above. 

As there is in acids but one element unknown (or vari- 
able), the acids are often called by pet names, using this 
element as an adjective; thus, 
H N0 3 = nitric acid, instead of hydrogen nitrate. 
H 2 S0 4 = sulphuric acid, instead of hydrogen sulphate. 
H 2 S0 3 = sulphurous acid, instead of hydrogen sulphite. 

In the pet name of binary acids both elements are used; as H CI "= 
hydrochloric acid (or chlorohydric), instead of hydrogen chloride. 
(H CI has still another pet name used in commerce, a commercial name, 
muriatic acid. ) As you should not call a stranger by his pet name, so 
it is much better for you not to call any chemical compound by its pet 
name till you know its composition thoroughly and its chemical (system- 
atic) name. 

Note. — Most chemical compounds have one or more pet names, used 
in commerce, by miners, by workmen in the arts, by mineralogists, or 
by pharmacists. In works on chemistry these names are often inserted 
after the chemical name (or vice versa). The druggist must learn at 



32 CHEMICAL PRIMER. 



least three different names for nearly all substances. For example, a 
boy calls for "copperas." The druggist thinks "iron sulphate" and 
takes it from a bottle labeled, in Latin, "Ferri fikilphas." The older 
chemists say sulphate of copper, of magnesia, of lime, of soda, of po- 
tassa (or potash), for respectively, copper, magnesium, calcium, sodium, 
and potassium sulphate. 

If the molecular composition of the acids has been mastered, they may 
be called by their pet names hereafter. Notice that the formulas for all 
acids begin with H, while formulas for all bases end in the grouping 
HO. [Confine this colloquial use of " pet " to the class-room.] 

Write formulas for the following: — 

phosphoric acid acetic acid 

chromic acid boracic acid 

citric acid pyrophosphoric acid 

hydrofluoric acid sulphurous acid 

Inspection of the following questions will show that the 
methods of solution are the same, whether the com- 
pound is a binary or a ternary. 

1. In 580 kgs. of the iron ore, ferrous carbonate (Fe C0 3 spathic iron), 
how much iron? 

Fe = 56 at. wt. 116 Fe C0 3 = 56 Fe 

C = 12 " 1 " = T X6- of 56 Fe, 

3 = 4S " 580 kgs. " = |f°- of 56 kgs. Fe; = 



Fe C0 3 =116 mol. wt. 280 kgs.— Ans. 

2. How much zinc sulphate could be made from 130 kgs. of Zn? 

Zn = 65 65 Zn = 161 Zn SO, 

S = 32 1 Zn = i of 161 Zn SO, 

Do * 

0, = 64: 130 kgs. Zn = \»p of 161 kgs. Zn SO, = 

Zn SO, = 161 322 kgs.— Ans. 

3. In 100 kgs. of potassium arsenate how much arsenicum? 

4. In 150 gms. of mercuWc (Hg = dyad) nitrate, how much mercury? 

5. In 15 gms. of mercunws (Hg 2 == dyad) nitrate, how much mer- 
cury ? 

6. How much lead carbonate (white lead) could be made from 50 kgs. 
of lead? 



REACTIONS. 



33 



CHAPTER XIV. 



We have seen that chemical changes are called reactions. 
There are various classes of reactions, of which the sim- 
pler should be thoroughly mastered by beginners, and the 
more complex let severely alone. 

Class 1. 

Reaction by Direct Union (or Separation). 

ExpePvIMext. 1.— Heat a small 
quantity of sulphur well mixed 
with fine copper filings on a 
broken test-tube or other piece 
of glass; a reaction takes place 
and copper sulph/V/e is formed. 
Reaction (atomic): Cu -f- S = 

copper sulphur 

(red) ivellow) 

CuS 

copper sulphide 
(black) 

Exp. 2. — In a test-tube of 
hard glass place a small quan- 
tity of mercuric oxide (red) and 
close by rubber cork through 
which passes a fine glass tube 
connected to rubber tubing (Fig. 3). Place mouth of tube below the 
surface of water and heat test-tube to dull redness. The oxygen sepa- 
rates from the mercury and escapes bubbling through the water, while the 
mercury condenses in a ring upon the colder part of the test-tube. (An 
arrow indicates an escaping aas.) 

/ 
Reaction: Hg = Hg + 

red solid liquid invisible 




34 CHEMICAL PRIMER. 

Exp. 3. — Burn a small piece of magnesium ribbon in the air; the oxy- 
gen of the air unites with the magnesium, forming magnesium oxide. 

Reaction: Mg + = Mg 

magnesium oxygen magnesium oxide 

1. How much Mg could be made by burning 30 gms. of Mg? 

2. If you make 80 gms. of Mg 0, how much Mg must you take ? 

Air is composed of one part by volume of the gas oxy- 
gen and about four parts by volume of the gas nitrogen 
(with traces of carbonic oxide and vapor of water, etc.). 
Burning, or combustion, is, in general, the rapid union 
of a substance with oxygen. The temperature at which 
the substance takes fire, i. e., unites rapidly with the oxy- 
gen of the air, is called the igniting point (i. e., kindling 
point). Of course, the product of the burning will be 
an oxide, 

Exp. 4. — Burn some sulphur in a bottle containing a small quantity 
of water. (See Fig. 13 and Exp. 23. S in burning always acts as a 
tetrad.) 

Reaction (a): S -j- 2 = S0 2 (a gas) 

Close the mouth of the bottle and shake; 

Reaction (b): S0 2 + H 2 = H 2 S0 3 (an acid) 
Test for the acid by litmus paper. 

Exp. 5.— Scrape some fine powder from a piece of quicklime into a 
test-tube of water; 

Reaction: Ca + H,0 = Ca 2 HO (a base) 

quicklime water-slaked lime, 

a soft solid, part 
of which dissolves 

Test for the base by litmus paper. 

The last two reactions reveal the fact that there are different kinds of 
oxides. 

The two principal classes of oxides are:— 

1. Acid-forming oxides. 

2. Basic oxides. 



REACTIONS. 35 



The first are oxides of negative elements and they unite 
directly with water to form acids, as in reaction (b) of 
Exp. 4. 

The second are oxides of positive elements (metals) and 
unite directly with water to form bases, as in reaction of 
Exp. 5. 

Acid- forming oxides are often called anhydrides (without water), 
since they may be considered as acids deprived of water, as S0 2 = sul- 
phurous anhydride. The older chemists called them acids directly, as 
S0 2 = sulphurous acid. 

Basic oxides are often called bases, (It is impcrtant to know that 
this is still correct usage. Indeed, some authors give as the definition, 
"A base is a metallic oxide," and these authors call the true base a 
"hydrated oxide" or "hydrated base.") Basic oxides unite with acids 
to form salts, just as the true bases do, and by a reaction very similar. 

It will be seen that the term "base" is used by chemists somewhat 
indefinitely. In a wide sense it is used of any substance that will unite 
with an acid to form a salt (or a salt and water, or a salt with free hy- 
drogen, etc.). In this wide sense it would include: — 

1. Positive elements (or groupings). 

2. Basic oxides. 

3. Positive hydrates. 

The word "base" has thus far been used in this last and restricted 
sense. The word " alkali ' is also used in a comprehensive sense. The 
sense of the words, however, may easily be told from the connection. 

There are five great agents tending to produce chemical 
change, and these are often used by chemists to accomplish 
this result, — Heat (Exps. 1, 2, 3, 4, etc.), Light (Exps. 6, 
8, 69, 70, etc.), Water (or Solution, Chap. XV, etc.), Elec- 
tricity (Chap. IV, etc.), and the so-called Tital Force 
(Organic Chemistry). Time is frequently an important 
condition in securing chemical change. 



36 



CHEMICAL PRIMER. 



CHAPTER XV. 



Class 2. 
Reaction by Change of Partners. 

Exp. 6. — Dissolve one gram of sodium chloride (common salt) in nine 
grams of (distilled) water (a ten per cent, solution). Dissolve one gram 
of silver nitrate (lunar caustic) in nineteen grams of water (a five per 
cent, solution). Pour a little of the first solution into a small test-tube, 
and into it let fall a few drops taken from the second, by means of a 
glass tube pipette dipped beneath the solution and closed at the opposite 
end by the finger. A beautiful, white, curdy solid (silver chloride) is 
formed by the reaction, and slowly settles to the bottom of the test-tube. 




Fig-. 4. (a)— lead post, (b)— rubber band. 

Taking this reaction as the type of its class, we may 
learn much from it. 



kE ACTIONS. 



37 



Just as by change of partners, 



f George ) 
\ Lucy j 



r 1 f Charles ) 
+ | E 



Liinma 



* 



f George ) 
( Emma j 



+ 



( Charles } 

X Luc y J 



so 



Na CI + Ag N0 3 = Na N0 3 + Ag CI 



sodium 
chloride 



siiver 
nitrate 



sodium 
nitrate 
Soluble solid 
and therefore 
not precipi- 
tated, but re- 
maining in 
solution. 



silver 
chloride 

Insoluble 
solid, called 
a prvcijJt- 
tate. 



oluble \ 
called ( 
recipi- j 



Note. — This is a very simple and frequent method of reaction. 
Like preceding colloquialisms, " change of partners" should be con- 
fined to class-room use. After reaction proceed as in Exp. 7. Care- 
fully label the vials in which precipitates are preserved. It will be 
noticed that Ag CI turns dark when exposed to the light. (See Silver.) 

Water favors chemical change. 

(There are exceptions. — Water does not favor ordinary combustion.) 
Thus, two substances in solution will react with each other, which 
would not if they were mixed dry. Iron rusts (unites slowly with the 
oxygen of the air, forming ferric oxide Fe 2 O a ) if exposed to the air wet. 
Knives and forks must be wiped dry, else they rust. Solution divides 
a substance more minutely and -evenly than can be done by any other 
method of mechanical division. Solution separates the molecules. For 
instance, if a teaspoonful of common salt be thrown into a barrel of 
water and dissolved, molecules of salt may be found in every drop of 
the entire barrel. They seem to move among the molecules of water 
freely, the water giving them an atmosphere in which they easily per- 
form reactions with other substances. The water is not written in the 
reaction, unless it really takes some part in the atomic changes. 

When a substance dissolves in water, and unites chemically with the 
water to form another compound (as in reactions of Exp. 4 and 5), this 
is not a mere solution, but something more. In a mere solution the sub- 
stance goes into the water (somewhat as grains of sand might be poured 
into a measure of peas) without uniting with the molecules of water at 
all. 

A gas, as we have already learned, may be dissolved in water as well 
as a solid. 



38 



CHEMICAL PRIMER. 



A liquid may also be dissolved in water, but we speak of the liquid 
not as dissolved in water, but as diluted with ivater (or mixed) and we 
do not speak of the resulting liquid as a solution. (See Volatile Oils.) 

When as much as possible of the substance is dissolved in a certain 
amount of water, the solution is said to be a saturated Solliti.011. 

Many solids and gases are insoluble in water. (Some liquids will not 
mix with water and therefore cannot be diluted with water.) Often 
these may be dissolved in other liquids, as alcohol (ethyl hydrate), hy- 
drochloric acid, etc. The liquid dissolving the substance is called a 
solvent. 

Whenever two substances, one at least being in solution, react, forming 
a solid insoluble in the liquid, the resulting solid, as it usually quickly 
falls to the bottom, is appropriately called a precipitate. If soluble 
solids are formed at the same time, they of course remain in solution. 
If gases are formed in the reaction, they usually come off the liquid in 
bubbles. Substances which react with each other as in the above reac- 
tion, especially those that are much used in the chemical laboratory, are 
called reagents. 

Exp. 7. — Into a test-tube containing silver nitrate solution let fall a 



few drops of dilute hydrochloric acid, 
of partners, as in Exp. 6, thus: — 

Reaction: H CI + AgND 3 



hydrogen 
chloride 



silver 
nitrate 



The chemicals react by change 

+ 



HXO. 

hydrogen 
nitrate 



AgCl 

silver 

chloride 

^precipitate) 



Precipitates may be separated from the liquid by filtration. 
and fold some filter paper, thus: — 



Cut 




and place it on a funnel (tunnel), pouring the contents of the test-tube 
upon it. 



REACTIONS. 



39 




Fig. 6.— Section of Filter Stand. 

The precipitate remains upon the filter, while the liquid called fil- 
trate passes through. Wash the precipitate, to free it entirely from 
the filtrate, by forcing with the breath water in fine spray from wash 
bottles upon it. Remove the precipitate and dry upon glass, or dry 
before removing, a^ is sometimes more convenient. 




Fig. 7. 
Bottle for cold water. Flask for hot water. 



40 



CHEMICAL PRIMER. 



CHAPTER XVI. 



Class 2. — (continued.) 

Exp. 8. — Place a very little ferrous sulphide in a small bottle, and 
pour upon it dilute sulphuric acid. [In some cases the reaction is not 
prompt. This depends upon preparation of Fe S used. Heat acid and 
Fe S in test-tube, Fig. 3 and Fig. 18.] 

y 

Reaction: Fe S + H 2 S0 4 = Fe S0 4 + H 2 S 

As H 2 S is a gas, it comes off in bubbles. 
Close the mouth of the flask by a rubber 
cork, through which a fine glass tube 
passes. By means of a rubber tube and 
another glass tube, allow the gas to pass 
into water. As the gas is soluble (three 
volumes in one of water), we have a solu- 
tion of the gas. Set this aside in dark 
bottle, as a reagent. (It decomposes in 
about four weeks and becomes worthless. ) 




. 8.— Making- solution 
hydrogen sulphide. 



Caution, — FLS is a poisonous gas, and Exp. 8 should be performed 
under a gas chimney, or near a window with an outward draft. (To 
breathe a small quantity mixed with air will, however, do no harm. ) 
This gas is largely used in the laboratory, and chemists are often more 
careless with it than is consistent with health. Learn to be cautious and 
careful in performing all experiments, following directions minutely. 

Exp. 9. — To a solution of lead acetate in test-tube add drop by drop 
solution of H 2 S. (Reagents are hereafter presumed to be in solution.) 



Reaction: 



Pb 2 C 2 H 3 2 

lead 

acetate 



+ H 2 S = PbS + 

hydrogen lead 

sulphide * sulphide 

(black precij)itate) 



2 H C 2 HA 

hydrogen 

acetate 



It will be noticed that when the hydrogen changes partners with the 
lead atom and takes the acetate grouping, the hydrogen and acetate 
grouping being univalent, they are matched one to one, giving us two 



REACTIONS. 



41 




molecules of acetic acid. It would he incorrect to write H 2 2 C 2 H 3 2 . 
Never put tiro monads with two monads in reactions^ but always one 
monad with owe monad, and if there be two of each, double the mol- 
ecule. 

Just as we must take tivo monads to match one dyad 
in a binary, so we must take two molecules containing 
monad partners to react with one molecule containing 
dyad partners. 

Exp. 10. — To mercuric chloride (corro- 
sive sublimate) add drop by drop potas- 
sium iodide. (Fig. 9 represents a conven- 
ient test-tube stand. ) 

Reaction: Hg Cl 2 + 2 K I = 

mercuric potassium 

chloride iodide 

Hgl 2 + 2KC1 

mercuric potassium 

iodide chloride 

(red precipitate) 

If too little is added, the precipitate dis- 
Fig. 9.-(A) rubber band. ^^ if toQ much is addedj the precipi . 

tate dissolves, i. e., the precipitate dissolves in excess of either re- 
agent. Xotice that the molecule of mercuric chloride contains dyad 
partners (Hg = a dyad, and Cl 2 two monads = a dyad,) while potas- 
sium iodide contains monad partners; therefore, we must take two mol- 
ecules of the latter to react with one of the former. 

Exp. 11. — Into a solution of arsenofts oxide (dissolve in hot water and 
filter) let fall a few drops of dilute hydrochloric acid. 

Reaction (a): As,0 3 + 6 H CI = 2 As Cl 3 + 3 H 2 

As 2 3 , a molecule containing hexad partners, requires six molecules 
of H CI to react with it. As Cl 3 , arsenous chloride, being soluble in 
water, does not appear as a precipitate. Into the test-tube drop solu- 
tion of H 2 S. 

Reaction (b): 2 As Cl 3 + 3 H 2 S = As 2 S 3 + 6 H CI 

(lemon yellow 
precipitate) 

In reaction (b) we must take two molecules containing triad partners 
(As Cl 3 ) to react with three molecules containing dyad partners (H 2 S), 
just as we take two triad elements to match three dyad elements in 
forming binaries. In the second member of the equation we must be 



42 CHEMICAL PRIMER. 

careful to match tlie atoms according to their "strength" and to mul- 
tiply the molecules afterward, so that the number of atoms of any ele- 
ment shall be the same in both members. 

Exp. 12. — To lead acetate (sugar of lead) add magne- 
sium sulphate. 

Reaction : Pb 2C 2 H 3 2 + Mg SO, = Pb S0,+ Mg 20 2 H 3 O 2 

a poison its antidote insoluble and soluble, but harm- 

therefore harmless less salt 

(white precipitate) 

Inspection of this last reaction will reveal the exact 
nature of a chemical antidote. Let the test-tube repre- 
sent the stomach. A chemical antidote is a substance 
which will unite with the poison, forming insoluble or 
harmless compounds, or both. (See Antidotes.) 

Exp. 13. — To calcium hydrate (lime water) add ammonium carbonate. 
Reaction: Ca 2 HO + (H 4 :N") 2 C0 3 = Ca C0 3 + 2 H,N HO 

white precipitate 
(chalk) 

Inspection of the following questions and the method 
of solving them will open to the attentive student a wide 
field for careful and accurate work. To such a student 
the problems are not difficult. 

1. From 542 mgs. of mercuric chloride, how much mercuric iodide 
could be made by adding potassium iodide? 

Reaction: Hg Cl 2 + 2 K I - Hg I 2 + 2 K CI 
200 200 

71 254 

271 mol. wt. 454 mol. wt, 

(will make) 

271 mgs. Hg Cl 2 = 454 mgs. Hg I 2 
1 " " ^^ T of454HgI 2 

542 " " = |4f of 454 mgs. Hg I 2 = 908 mgs.— Arts. 

2. How much mercuric chloride will be required to make 150 gms. of . 
mercuric iodide (adding K I) ? 



REACTIONS. 43 



Reaction: Hg CI, + 2 K I - Hg I 2 + 2 K CI 
200 200 

71 254 

271 454 

would require 

454 Hg I a = 271 Hg Cl 2 

1 " = T i T of 271 Hg Cl 2 
150gnis. " = Jfo f 271 gms. Hg Cl 2 = 89|§f gms.— Ans. 

3. How much potassium iodide would be required to make 227 gms. 
ofHgI 2 ? Ans. 166 gms. 

4. How much potassium chloride could be made by using 996 gms. of 
potassium iodide? Ans. 447 gms. 



CHAPTER XVII, 



Class 3. 
Reaction of Acid and Base. 

When an acid and base are united, the result is a salt 
and water. The acid is said to neutralize the base (or 
vice versa). 

Exp. 14. — To barium hydrate add drop by drop sulphuric acid. 
Reaction: Ba 2 HO + H 2 S0 4 = Ba S0 4 + 2 H,0 

base acid salt water 

(white precipitate) 

Exp. 15. — To oxalic acid add calcium hydrate. 

Reaction: H 2 C 2 4 + Ca 2 HO = Ca C,0 4 + 2 H 2 

acid base salt water 

(white precipitate) 

Exp. 16. — To sodium hydrate add drop by drop acetic acid, till solu- 
tion is neutral to litmus paper. 

Reaction: Na HO + H GJET 3 2 = Na C 2 H 3 2 + H,0 

base acid salt watev 



44 



CHEMICAL PRIMER. 




10.— Water Bath. 



There is no precipitate, be- 
cause sodium acetate is soluble 
in water. 

Filter to remove -any slight 
solid impurities and evaporate 
to dryness in evaporating dish 
(or beaker) over a water bath, 
?. e., steam bath. (See Fig. 10.) 
Sodium acetate, a solid, remains. 
Xote. — Whenever a water 
1 ath is recommended, the simple 
meaning is that the evaporation 
be carefully done, so as not to 
scorch or sublime the residue. 
The water bath prevents the heat from rising above 100° C. It may be 
dispensed with in most cases if sufficient care be used. 

Class 3 is only another form of Class 2. Notice that the HHO 
(hydrogen hydrate) which we should get, if we wrote according to 
Class 2, simply shrinks to the binary H 2 0. 

Class 4. 

Reactions of Acids and Carbonates. 

In these reactions, the carbonate grouping breaks up. 
When an acid unites with a carbonate, the result is a 
salt, water, and carbonic oxide (a gas). The law in re- 
gard to molecules containing partners of different strengths 
holds good, as in the last two cases. This reaction is fre- 
quently used by the druggist and pharmacist. 

Exp. 17. — To acetic acid add sodium carbonate (solid or in solution) 
till effervescence ceases. (Effervescence is the bubbling caused by the 
rapid separation of a gas from a liquid.) 

/ 

Reaction: Ka 2 C0 3 + 2 H C 2 H 3 2 = 2 Na C 2 H 3 2 '+ H 2 + C 2 



salt 
(soluble) 



carbonic 
oxide 



Filter, evaporate filtrate, and preserve. The salt is obtained as in 
Exp. 16. The heat of evaporation entirely expels anyC 2 that maybe 
held in solution after the reaction. 



REACTIONS. 45 



Exr. IS. -Into dilute citric acid let fall an excess of finely pulverized 
calcium carbonate (marble). When effervescence ceases, boil (to pre- 
cipitate any dissolved carbonate), filter, evaporate, and preserve as before. 

/ 
Reaction: 3 Ca C0 3 + 2 H 3 C 6 H 5 7 = Ca 8 2 C 6 H 5 7 + 3 H,0 + 3 C0 2 



carbonic 
oxide 



Class 4 is a modification of Class 2. The H 2 C 3 which we should 
get according to Class 2, simply breaks up into the two binaries H 2 
and C 2 . 

Notice, in evaporating, that this salt (calcium citrate) 
is less soluble in hot than in cold water; an exception to 
the general rule, that "for equal volumes, hot water dis- 
solves move of a solid than cold water. 

As a rule, "hot water dissolves less of a gas than an 
equal volume of cold water." Indeed, many gases not 
only will not dissolve at all in boiling water, but may be 
completely expelled from water, in which they may have 
been previously dissolved, by boiling it. 

Before leaving these chapters on reactions, the student should be able 
to write promptly any reaction belonging to either of the four classes, 
provided he has the names of the two substances given and the tivo refer- 
ence tables before him. 

MISCELLANEOUS PROBLEMS. 

1. Write formulas for five binary acids. 

2. Write formulas for ten ternary salts. 

3. Write formulas for two binary salts. 
-4. Write formulas for six ternary acids. 

5. Write formulas for five bases. 

6. In 150 gms. of arsenous oxide, how much As? 

7. In 1000 gms. of silver chloride, how much silver? 

8. How much mercuric sulphide could be made by using 50 kgs. of 
mercury (Hg")? 

9. Reaction when phosphorus burns in air? 

10. When carbon burns? 

Reactions when the following are united: — 

11. Stannous chloride (Sn") and hydrogen sulphide? 

12. Copper sulphate and sodium hydrate? 



46 



CHEMICAL PRIMER. 



13. Sodium carbonate and hydrochloric acid? 

14. Ammonium carbonate and calcium hydrate? 

15. Potassium hydrate and sulphuric acid? 

16. Calcium hydrate and citric acid? 

17. Potassium carbonate and tartaric acid? 

18. Acetic acid and magnesium carbonate? 

19. To make 190 gms. of magnesium chloride (by adding H CI), how 
much magnesium carbonate must be taken? 

20. How much arsenous oxide, As 2 3 (white arsenic) was contained 
in a vessel full of water, from which 15 mgs. of arsenous sulphide was 
precipitated (by adding H CI and H 2 S)? 



CHAPTER XVIII. 



OXYGEN. 

Exp. 19. — Carefully pulverize in a mortar a small quantity of potas- 
sium chlorate, and, having mixed it thoroughly with an equal bulk of 
pure manganese dioxide, introduce into a small copper retort. Heat by 
a strong alcohol flame, or flame from a Bunsen's burner. Collect in 
receivers over a pneumatic tub, as represented in Fig. 11. [A glass 
flask heated upon a sand bath (iron basin filled with sand, Fig. 21) may 
be used in place of the copper retort. ] 

Reaction: K CI 3 = K CI + 3 




Fig. 11. 
(a)— retort stand; (b)— retort; (c) — receiver; (d) -pneumatic tub; (e)— receiver removed. 



OXYGEN. 47 



Note. — The presence of Mn 2 causes the to come off more steadily 
and at a lower temperature, but as it takes no part in the reaction, (?) it is 
not written. The first bubbles that come off are composed principally 
of air from the retort and should be allowed to escape. The 
often looks cloudy, because small particles of the salt and oxide are 
carried over by the draft. These gradually dissolve or settle into the 
water. Three or four receivers should be inverted, and as fast as filled 
removed by means of a small, shoal tin cover, holding a little w^ater, to 
prevent the escape of the gas. Small quantities of may be conven- 
iently made by using test-tubes as retorts, test-tubes, or bottles, as 
receivers, and a beaker or basin as a pneumatic tub. (See Fig. 3.) 
Avoid heating too rapidly in one place, by carrying lamp or burner back 
and forth slowly, so that test-tube shall pass through the bottom of the 
flame, nearly touching the wick or burner. 

Caution. — K CI 3 must not be heated alone. Commercial Mn 2 is 
sometimes adulterated with carbon (pounded coal) and when mixed 
with K CI 3 and heated, the mixture explodes violently. Test by 
heating in test-tube a small quantity of the oxide and chlorate mixed, 
unless the former is warranted to be pure. The delivery tube must be 
removed from the water be/ore the heat is taken from the retort, other- 
wise, as the gas in the retort cools and contracts, the water is forced 
back along the tube by atmospheric pressure. The first that falls into 
the highly heated retort is instantly converted into steam, causing an 
explosion. Ordinary care will prevent any serious accident. The chief 
danger in breaking glass retorts is to the eyes. 

Learn here that an explosion is (generally) caused by the sudden con- 
version of matter from the solid or liquid to the gaseous state. 

Oxygen is a colorless gas, without odor or taste. As 
we have inferred from the formulas thus far used, it is a 
very abundant element. It exists free (uncombined) in 
the air, forming one-fifth its volume. Chemically com- 
bined with other elements, it forms by weight eight-ninths 
of water, one-half of minerals, three-fourths of animal 
tissues, and four-fifths of vegetable tissues; in short, so 
far as we know, about two-thirds of the earth. 

Exp. 20. — Into a receiver (bottle) of 0, plunge a taper having a live 
coal upon the end, it immediately bursts into a blaze. Quickly remove 
and blow out the flame. Repeat the relighting from twenty to forty 



48 



CHEMICAL PRIMER. 



times, as may easily be done before the gas is exhausted. Do not plunge 
deeper than is necessary to rekindle, as this uses up the rapidly. 

Wood, oil, tallow, etc. (things that we ordinarily burn), 
are composed principally of H and C, and are therefore 
called hydrocarbons. When hydrocarbons (as the taper 
in the experiment) burn, two reactions take place, viz. : — 
H 2 + O = H 2 (steam) ) Gaseous prod- 
C + 2 = C0 2 (a gas) J combustion. 
Immediately after the is exhausted, pour into the receiver a very 
small quantity of water, and closing its mouth, shake at intervals. The 
C 2 gradually dissoh^es. 

Reaction: C 2 + H 2 .= H 2 C0 3 

acid forming acid 

oxide 

Test by litmus paper, but as H 2 C0 3 is a very weak acid, litmus paper 
must remain a little time in it. 

O is a vigorous supporter of combustion. is heav- 
ier than air, for we hold the mouth of the receiver 
upward to retain the gas. 

Water is the standard of specific gravity for solids and 
liquids, and air for gases (in physics). Sp. gr. of air is 1, 
of O 1.1+. But in chemistry, hydrogen (which see) is 
made the standard for gases. 

Exp. 21.- —Straighten a narrow steel(Fe) watch-spring 
and file the end bright. Attach (Fig. 12) a very short 
piece (head) of a common match, as kindling for the 
steel. Ignite by flame and quickly plunge into a 
receiver of 0. The steel burns vividly 

Reaction: Fe d -J- 4 = Fe 3 4 

(triferric tetroxide 

black or magnetic 

iron oxide) 

If a large receiver is used, and the head of the 
match is attached to the spring by winding a very 
fine iron wire closely about both, the experiment is a 
very brilliant one. This reaction is an irregular one, 
that is, the strength of iron is apparently not accord- 
ing to the Table. This oxide is often called ferroso- 
. ferric oxide, and is supposed to be formed by the 
direct molecular union of the other two (Fe 2 3 + Fe O — Fe 3 4 ), these 
being formed also in minute quantities by the reaction. 




OXYGEN. 



49 



If the air were pure O, our iron stoves would take 
fire, and a general conflagration would spread over the 
earth. We could not, for any length of time, breathe 
pure O, as it would over stimulate the vital processes. It 
is diluted with four times its volume of the inactive gas, 
nitrogen, forming the proper mixture to be respired. (See 
pages 34, 58, and 67.) 

Exp. 22. — Charcoal bark, a small part of which has been heated to a 
live coal, plunged into (by means of a Cu wire twisted about it), 
bursts into a vivid combustion. 

Exp. 23.— Repeat Exp. 4 in jar of 0. (Place 
S on chalk in a combustion spoon. Copper wire 
twisted about a piece of chalk makes a good com- 
bustion spoon. ) 

Exp. 24. — Cut under water, quickly and care- 
fully dry between pieces of blotting-paper, a 
small piece of phosphorus (not larger than a grain 
of wheat). Place in a combustion spoon, ignite 
by hot wire, while lowering into a large jar of O. 
containing at the bottom a little water. _A 
blinding light is caused by the combustion. 
Reaction: P 2 + 5 = P 2 5 

dense white 
fames 

In a short time these fumes are dissolved in the water, and the follow- 
ing reaction slowly takes place : — 

P 2 5 + 3H 2 = 2H 3 P0 4 

acid forming 
oxide 

Test by litmus paper. 

Caution. — Handle P with great care, on no account touching it. 
The heat of the hand may inflame it, and its burns are dangerous. Its 
vapor is highly poisonous and must not be inhaled. The dense, white 
fumes should be immediately shut in by stopple attached to combustion 
spoon. (See Fig. 13.) 

O is an exceedingly active gas. It alone supports all 
ordinary burning that takes place in the air. To bring 
ihis gas in contact with the blood is the object of respiration 




50 



CHEMICAL PRIMER. 



in animals. The blood absorbs and carries O to all the 
tissues, the most prominent chemical change taking place 
in the body being that of oxidation. (See carbonic 
oxide. ) 

There is a peculiar form of condensed O, called Ozone. 
It is O in an allotropic state. It may be made in various 
ways, especially by the action of electricity on common 
O. It occurs in minute quantities in the air. It is even 
more active than O and is a powerful disinfectant. 

In ozone tainted meat rapidly loses its putrescent odor, because the 
foul material is oxidized, forming relatively wholesome compounds. The 
molecule of ozone may be represented thus 



oo 



with three atoms, 

that of oxygen being | qoj composed of two atoms, that is, three vol- 
umes of oxygen if it could all be changed to ozone would make but two 
volumes of ozone. A disinfectant destroys (not purifies) foul sub- 
stances and low forms of (organic) life called " germs," etc. 



CHAPTER XIX. 



HYDROGEN. 



Exp. 25. — Place in a small flask, or large test-tube (hydrogen gener- 
ator), some granulated Zn. Upon it pour dilute (10 per cent.) sulphuric 
acid. Close mouth of flask with perforated rubber cork, through which 
passes a fine glass tube. Collect H over pneumatic tub, as in Fig. 14. 

/ 
Zn + H 2 S0 4 = ZnS0 4 + H 2 

Note. — Collect several re- 
ceivers of the gas, and, after 
the reaction has ceased, filter 
the liquid remaining in the 
flask; evaporate filtrate, and 
the white salt, zinc sulphate, is 
obtained. If a drop of the fil- 
trate is placed on a piece of 
glass and set aside, away from 
the dust, beautiful crystals of 
the salt are left upon the glass. 




Fig. 14.— Making Hydrogen. 



HYDROGEN. 51 



Hydrogen is a colorless gas, without odor or taste 
(when pare). It is the essential constituent, as we have 
seen, in acids. Indeed, acids have sometimes been defined 
as "salts of hydrogen." H does not occur free, It has 
been condensed by cold and pressure, first, to a liquid and 
then to a white solid. II is not poisonous, but destroys 
life, just as water does, by shutting out the O. The lungs 
may be inflated with the pure gas without harm. 

Caution. — Gases made by beginners must never be 

breathed. As a rule, a gas is obtained absolutely pure 

with great difficulty. For methods of obtaining gases 

pure, see larger text-books or some treatise. 

Exp. 26. — Remove a jar of H, holding the mouth downward, and 
into it plunge slender lighted taper. The H takes fire and burns at the 
mouth of jar, but the taper is extinguished in the gas above. It may- 
be relighted by the burning H as it is being removed. 

H is lighter than air, for we hold the gas by keeping 
the mouth of the receiver downward. H is yery inflam- 
mable, i. e., its igniting point is low. It does not sup- 
port combustion (of hydrocarbons). 

Note. — Combustible bodies and supporters of combustion are relative 
terms. A jet of would burn in a jar of H just as well as a jet of H 
in a jar of 0. One as well as the other could be called the supporter 
of the combustion. 

Exp. 27. — Collect H from generator in test-tube by displacement of 
air. Pour upward into another test-tube, displacing the air. Test by 
igniting. 

Exp. 28. — Attach by rubber tube a clay pipe to generator and blow 
soap bubbles with H. They ascend and may be ignited in the air. 

Hydrogen is the lightest substance known, being about 
14i times lighter than air. Chemists take hydrogen as the 
standard of specific gravity for gases. With this stand- 
ard, "one-half its molecular weight is the specific gravity 
of any gas." (See Miscellaneous Questions, Chap. XXII, 
Note.) 



52 



CHEMICAL PRIMER. 




Exp. 29. — Fit a perforated cork, through 
which passes a glass tube, deeply into a new, 
dry porous cup (such as is used in Bunsen's 
battery). Melt over the surface of the cork 
sufficient paraffine (or tallow) to make it air- 
tight. Place the end of tube just beneath 
water in a beaker (Fig. 15), and cover the 
porous cup with receiver of H. The H passes 
by diffusion in through the pores of the cup 
much more rapidly than the air passes out, 
therefore bubbles of air are forced out through 
the water. Remove receiver and soon the 
water rises in the tube because of the diffusion 
of the H outward. 



Fig. 15. 



All gases possess power of diffu- 
sion, but the power is possessed' by H in an extreme de- 
gree. The diftusibility of gases is " Inversely as the 
square roots of their densities," the density (or sp. gr.) of 
any gas being, as given above, half its molecular weight. 

EXAMPLE. 



ITm— . \[ 

II density . W 
I of f 



1 

density 

of H 



diffusibili'y 
of H 



divisibility 
of O 



That is, H has four times the diffusive power of O, or dif- 
fuses four times as rapidly. H may leak through vessels 
that would retain O permanently. 

Exp. 30. — Close generating flask by a rub- 
ber stopple, through which passes a hard glass 
tube, with fine opening. After the air has been 
expelled by the H, ignite the jet. The appa- 
ratus is the "Philosopher's Lamp." Over the 
flame invert a cold, dry test-tube. It is be- 
dewed with moisture. 

H 2 + = H 2 

When H burns, the product is 

i6.— Philosopher's lamp, water (steam). The H flame gives 
little light, but great heat. The alcohol (ethyl hydrate) 




HYDROGEN. 



53 



flame gives little light and great heat, because alcohol 
contains much H. 

The flame of the oxy-liydrogen blowpipe melts many substances 
(as platinum), infusible in ordinary fire, the alcohol flame, or the flame 
from a Bunsen's burner. 




Fig. 17.— Section of oxy-hydrogen blowpipe. 

The H from the gasholder is first turned on and ignited, and after- 
ward the is turned on. [Gasholder is shown in Frontispiece 3.] 

Exp. 31. — Fill over a pneumatic tub a stout quart fruit jar one -third 
with 0, and the remainder with H. Wrap about it a doth; remove, and, 
holding the mouth downward, quickly ignite by means of a taper. A 
sharp explosion ensues. 

There are two reports heard as one, the second so closely follows the 
first. The first is caused by the sudden (but not greater than a few 
volumes) expansion of the gases heated by their union; the second is 
caused by (the steam suddenly condensing) the rush of the air from all 
sides to fill the partial vacuum. Caution. — Of course, H explodes 
when mixed with air. Care must be taken to expel all air from appa- 
ratus before igniting jets of H. Xever ignite large quantities of the 



Exp. 32. — Repeat the experiment of decomposing water as explained 
in connection with Fig. 1. 

This proves by Analysis the composition of water. If we explode 
two volumes of H with one of and find we have nothing but water left, 
we prove the composition of water by Synthesis. 

Water H 2 

The wonderful power of chemical affinity is shown in 



54 



CHEMICAL PRIMER. 



this compound. A union of the most inflammable sub- 
stance known with the most vigorous supporter of com- 
bustion, forms another substance which will extinguish 
fires. We have called this substance by its pet name, 
because it is so common a substance and so generally dis- 
tributed. Its systematic name (hydrogen oxide) is seldom 
used. We have already learned that water is the general 
solvent in nature, dissolving most gases and solids and 
diluting most liquids. 

Hard water contains minerals in solution ; soft water 
does not. 



Note. — In a narrower, but very common usage, only such water is 
called hard as contains in solution minerals that either react with soap, or 
hinder its solution (see Soap). Water containing such minerals as borax 
and potassium carbonate would be called in the laundry soft water. 
Water or soil containing potassium carbonate, sodium carbonate, etc., 
is often said to be ^alkaline,'' because these salts have an alkaline reac- 
tion upon litmus, and because the old chemists called the strongly posi- 
tive carbonates ''mild alkalies." (They called the strongly positive 
hydrates "caustic alkalies," and these hydrates are still frequently thus 
called.) 

Exp. 33. — In a test-tube place small 
pieces of marble and cover with dilute 
hydrochloric acid (ten per cent). 

Reaction (Class 4th) : — 
Ca C0 3 + 2 H CI = Ca Cl 2 + H 2 + C0 2 

By means of a delivery tube (Fig. 18) 
pass the gas through clear lime water 
(solution of Ca 2 HO, see Exp. 5) in a 
second test-tube. The lime water at 
first becomes milky because of white 
precipitate of Ca C0 3 . 

Reaction: Ca 2 HO + CO, = CaC0 3 + H 2 

base aci forming salt 

oxide 




HYDROGEN. 55 



Allow the gas to continue bubbling through the lime water. After 
all the Ca is thrown down as a carbonate, the CO a dissolves in the water. 
Carbonates dissolve hi water containing C0 2 in solution, but not in pure 
v iter. ) The water becomes clear again because the calcium carbonate 
is dissolved. This clear water is now water of "temporary hardness." 
Boil. The C0 2 in solution is driven off, and the calcium carbonate is 
again precipitated, being insoluble in pure water. 

Hardness produced by earthy (Ca. Mg. Sr. Ba., etc.) 
carbonates is called " temporary hardness,"' because the 
carbonate may be precipitated by boiling, leaving the 
water soft. The "fur" upon the tea-kettle is a precipi- 
tated carbonate. 

Hardness produced by earthy sulphates is called " per- 
manent hardness," because the water cannot be made 
soft by boiling. (See Soap.) 

The vapor of water in the atmosphere is essen- 
tial, not only to plant life, but to animal life as well. 
The earth would be a vast desert were it not that tons of 
water are constantly being carried up from the ocean by 
evaporation, so that the air currents may distribute it, 
not alone to fall as rain, but also to keep the atmosphere 
everywhere moist. 

Many substances, when they crystallize (assume a sym- 
metrical shape in solidifying), take up a definite amount 
of water, called water of crystallization. This may be 
expelled by heat, but the essential properties of the sub- 
stance are not changed. 

Exp. 34. — Heat in a narrow, deep test-tube of hard glass, small crys- 
tals of pure copper sulphate previously carefully weighed; the water of 
crystallization is expelled and part of it condenses in small drops on 
the cooler part of the test-tube. The blue color disappears. Wipe 
with dry cloth the water from the test-tube. Remove and weigh the 
sulphate. It has lost over one-third its weight, as the formula of crys- 
tallized copper sulphate is Cu S 0^, 5 ELO. Touch with a drop of water, 
the color slowly returns. Dissolve in a small quantity of water, evap- 



56 CHEMICAL PRIMER. 

orate slightly, and set aside to cool. Beautiful crystals of copper sul- 
phate form as the solution cools. 

Fine crystals of various substances may be formed in this way, viz., 
by making saturated solution of the substance (slightly evaporating), and 
setting aside for a few days. Making a collection of crystals will be 
found a very profitable exercise. 

Water of crystallization is not written in ordinary reactions of 
substances in solution, but must be taken into account in dealing with 
the dry solids. Of course a larger quantity of the crystallized solid 
must be taken to equal a smaller quantity of the uncrystallized, if the 
solid takes up water of crystallization. 

Some substances, such as sodium acetate (Na C 2 H 3 2 
3 H 2 0), sodium carbonate (Na 2 C 3 , 10 H 2 0), etc., when 
exposed to the air lose their water of crystallization, and 
crumble to powder. These are said to be efflorescent. 

Some substances, as potassium carbonate (K 2 C 3 ), 
when exposed to the air, absorb moisture and dissolve 
(or partially dissolve). These are said to be deliquescent. 

The law of physics, that "heat expands and cold con- 
tracts," does not hold with water in cooling from about 
4° (C) to 0°, through which space it steadily expands, until 
it freezes (crystallizes) at 0°. At the moment of freezing 
there is a sudden and great expansion. (See Plot b, 
Fig. 19.) The importance of this exception cannot be 
overestimated, for it makes ice lighter than water, and 
so prevents lakes and rivers from freezing solid. 

Water containing impurities in solution may be puri- 
fied by distillation. The water is placed in a retort, or 
" still," is heated, rises as steam (at 100°), which, passing 
through the condenser (supplied with cold water in 
direction of arrows, Fig. 19), condenses, and is collected 
in a receiver. Steam ("dry steam") is an invisible gas. 
That which is seen and often miscalled steam is steam 
condensed (or partially condensed) into minute globules 



NITROGEN. 



57 



of water and held in suspension (like dust) by the air or 
by the invisible steam. 




Fig. 19. — Retort, or " still," and condenser. Plot b— Effect of "cold" upon water. 



CHAPTER XX. 



NITROGEN. 

Exp. 35. — Place a piece of chalk on a tripod wire-holder, standing in 
a deep plate of water. Upon the chalk place a small piece of P. Ignite 
by hot wire and quickly invert a receiver over it. (Caution, Exp. 24.) 

p 2 + o 5 = pa 

soluble 
white 
fumes 

The P unites with the in the jar. 
The phosphoric oxide dissolves and the 
water rises by atmospheric pressure and 
fills one-fifth of the receiver, the space 
before occupied by the 0. N remains 
in the receiver above the water, neither 
burning nor supporting the combustion 
of the remaining phosphorus. (See 
Phosphorus,) 
Fig. 20. 




58 CHEMICAL PRIMER. 

Nitrogen is a colorless gas, without odor or taste. It 
forms by volume i of the atmosphere. N is not poison- 
ous, and destroys life only by shutting out O. It is not 
inflammable and it does not support combustion. It is 
a very inert element. It dilutes the active O of the air, 
and -the mechanical mixture is thus fitted for respiration. 
Some of its compounds are by no means inert. For ex- 
ample, "nitro-glycerine," the violent explosive, is glyc- 
eryl nitrate, and the deadly poison, prassic acid, is hy- 
drogen cyanide. No one can predict with certainty the 
character of a chemical compound from the nature of its 
constituents. 

It might be supposed that, N being lighter than O, the 
air would separate into two layers, the heavier, O, sinking. 
The two gases, however, are kept thoroughly mixed by 
the law of diffusion of gases. 

N 2 O^ hyponitrous oxide (acid-forming ?} 

N 0, nitrogen dioxide (called so because formula was thought to be 
N, 2 ). 

N 2 3 , nitrous oxide (acid-forming). 

N 2 O^, nitrogen tctroxide (or peroxide, at high temperatures, N (X). 

N 2 5 , nitric oxide (acid-forming). 

These oxides illustrate well the great law of multiple 
proportions. When one substance unites chemically with 
another, it is in some definite proportion, or multiple of 
that proportion. Whenever substances are united phys- 
ically (mechanically, as in alloys of metals, etc.) they 
may be united (mixed) in any proportion. 

Note. — There is a third class of indifferent oxides, as N" 0, neither 

acid-forming nor basic. The pupil need not give any attention, however, 
to this class. All the positive indifferent oxides, as Mn 2 , Ba CK , K. 2 
4 , Pb 2 , having more than the basic, are called peroxides. There 
are still other oxides which belong not strictly to either of the three 
classes, but form acids or bases irregularly by decomposition, as N 2 4 and 
Fe 3 O^. For preparation of N 2 3 and-N 2 5 see larger text-books. 



NITROGEN. r>9 



Exp. 36. — Heat in flask ammonium nitrate and collect gas over pneu- 
matic tub of w inn water. 

/ 
H 4 N N0 3 = 2 H,0 + N 2 

Hyponitrous oxide ("nitrous oxide" laughing gas"), 
inhaled with a small proportion of O, produces a peculiar 
intoxication, hence its name of "laughing gas." If the 
pure gas is inhaled, it soon produces insensibility. It is 
much used as an anaesthetic by dentists and by sur- 
geons in minor operations. It may be kept in liquid state 
in iron cylinders. (See Caution, under Hydrogen, Exp. 

Exp. 37. — To small pieces of copper acid dilute (50 per cent.) nitric 
acid, red fumes appear in generator (see Exp. 38), but a colorless gas 
collects over the tub. 

Reaction (irregular, don't attempt to remember it) : — 

/ 
Cu 3 -f- 8 H K 3 = 3 Cu 2 1ST 3 +/4 H 2 +2X 

nitrogen 
dioxide 

After the action has ceased, filter water in flask, evaporate, and obtain 
blue crystals of Cu 2 X 3 . 

Exp. 38. — Admit to test-tube containing IS" a bubble of (or air). 
Red fumes of N 2 4 appear. 

/ 

2NO + 0, = XA 

nitrogen 
tetroxide 

These fumes are very soluble in water, and the water slowly rises to 
take the place of the dissolved gas. If air is admitted, of course the 
water will not entirely fill the test-tube, as the X will remain undis- 
solved above the water. 



Exp. 39. — Into a test-tube put a small quantity (4 gms. ) of sodium 
nitrate (or K N0 3 ) and 2 gms. of sulphuric acid. Carefully heat. Col- 
lect nitric acid in a narrow, deep test-tube, well cooled by sinking to its 
mouth in cold water. [Sink test-tube by tying stone to the bottom. 
Don't breathe the fumes. ] 

2 Na N 3 + H 2 S 0, = Xa 2 S 4 + 2 H N 3 



CO CHEMICAL PRIMER. 



Nitric acid (old name aqua fortis) is prepared by heat- 
ing sulphuric acid with sodium nitrate (but see acid-;$alts). 
It is a colorless (if pure), fuming, corrosive liquid. 

Exp. 40. — Place a quill in HX0 3 and heat. The quill, turns yellow. 

Exp. 41.— To dilute H N0 3 add a crystal of Fe S0 4 ; then add a few 
drops of H 2 S0 4 . A brown compound (Fe SO^, N 2 C^ slowly forms 
about the crystal. This is a good test for H N 3 and other nitrates. 

Exp. 42. — Throw a small crystal of potassium nitrate upon a red-hot 
coal. The coal burns rapidly (almost explosively). 

Nitric acid stains organic matter, as the skin, nails, 
etc., a dingy yellow. It is a powerful oxidizing agent, 

as are all the other nitrates. 

Exp. 43. — Spread upon a piece of clean copper (also upon a piece of 
iron) a thin layer of paraffine. Write upon each, taking care not to 
scratch the metal. Upon the writing put nitric acid (50 per cent.). It 
etches the words by oxidizing the metals, dissolving and uniting with 
the metallic oxides. 

Nitric acid is used in etching upon copper and iron 
(copperplate, swords, razors). 

Exp. 44. — Into a test-tube containing nitric acid, drop a piece of gold- 
leaf and heat. It does not dissolve. Add a few drops of hydrochloric 
acid. The gold rapidly dissolves, forming Au Cl 3 in solution. 

Nitric acid (about 3 parts) and hydrochloric acid (5 

parts) form aqua regia, the solvent of gold (and plati- 
num). 



Exp. 45. — Place in a flask a little ammonium chloride (sal ammoniac) 
with an equal weight of calcium oxide (quicklime), each finely pulver- 
ized. Add a little water and, quickly closing flask, heat upon sand bath. 
Dry gas by passing through bottle containing Ca 0. Collect by dis- 
placement of air in receiver. (See Fig. 21.) ["Drying tube" may be 
dispensed with and gas passed directly from flask into receiver. Don't 
breathe too much of the gas.] 

y 

2H 4 XC1 + CaO ~ CaCl 2 + H,0 + 2H,X 



NITROGEN. 



61 




Fig. 21. — A — sand bath; B—drjing* tube; C— receiver. 

Exp. 46 (45 concluded). — Quickly close mouth of bottle of ammonia 
by perforated rubber cork, through which passes a glass tube drawn to 
a fine point and connected with water colored red by slightly acidulated 
litmus solution. Hasten the action by forcing air into lower flask 
(through tube A B, Fig. 22, till a few drops of water reach the receiver 
(C) of ammonia. The gas dissolves so rapidly in the water that a par- 
tial vacuum is formed, and the outside atmospheric pressure acting 
through A B produces the "ammonia fountain." The water turns blue 
as it enters the receiver. 

Ammonia is a colorless 
gas, with pungent odor. It 
is much lighter than air. It 
is very soluble in water, 
700 gals, dissolving in a 
single gallon of water at 15° 
(1000 vols, at 0°, see coal 
gas). It not only dissolves, 
but unites with water 

Reaction : — 
H b N + H 2 = H 4 N HO 
forming ammonium hydrate 
("ammonia water," harts- 
horn, etc.). 

; / Fig. 22.— Ammonia Fountain. 




62 



CHEMICAL PRIMER. 



The ammonium grouping can be passed from compound to compound 
like an element, and hence is a compound radical. (See Ammonium.) 
In concentrated "ammonia water" there is probably a large excess of 
the gas dissolved (more than unites with the water). Ammonium 
hydrate (or ammonia in the presence of moisture) has a strong alkaline 
reaction. It has been called the "volatile alkali," because its effect 
upon vegetable colors is cnly temporary. Prove this by dipping red 
litmus paper into dilute ammonia water and noticing that the red color 
returns again after a few hours. When the color of cloth, stained by 
an acid, has been restored by "ammonia water," the ammonium salt 
should be thoroughly washed out with water, or the red spot returns. 
(See Chemistry of Cleaning.) 

" Evaporation COOls. " This means that when a substance evapo- 
rates it absorbs heat from what is near by. (See sulphur dioxide, ap- 
pendix.) Wet one hand and pass both hands rapidly through the air. 
The wet hand is sensibly colder from the evaporation of the water. 
Pour a little ether upon the thermometer bulb. The ether quickly 
evaporates and the mercury falls. 

A pressure of about 4| atmospheres (at 0°) converts 

gaseous into liquid ammonia. The evaporation of liquid 

ammonia produces intense cold ( — 40°). Advantage is 

taken in the arts of this fact to produce ice artificially. 

In a strong generator, A, is placed 
ice water saturated with ammonia 
gas (1,000 vols, in one). This is con- 
nected with an equally strong receiver 
D, by the tube B. Receiver D is 
placed in cold water. Heat is applied 
to A and the great pressure of 
escaping gas converts the gas into a 
liquid in D. Stopcock E is then 
closed. Water is now placed in ves- 
sel C. Generator A is cooled and 
E opened. The liquid ammonia in 
D evaporates and is reabsorbed by 
water in A. The evaporation pro- 
duces sufficient cold (takes away or 
Fig. 23.— Ice Machine. absorbs sufficient heat) to freeze icater 

in C. Other substances than ammonia may be used for this purpose, 

all, however, involving the principle of evaporation. 




CARBON. 63 



Nitrogen and hydrogen do not unite directly to form ammonia, but 
when decomposition is taking place in organic substances, and these two 
elements are leaving their old compounds, they unite. Elements just 
leaving their old compounds are said to be in the nascent state, and 
they have a much greater tendency to form new compounds. This ten- 
dency to form compounds is called Chemical Affinity. The ' ' strength ' ' 
of nascent elements remains the same as before, but their chemical 
affinity is increased. (See Exps. 81 and 85.) 



CHAPTER XXI 



CARBON. 



Carbon is a very abundant element. It forms a large 
proportion of vegetable and animal tissues, and is a prom- 
inent constituent of limestone, marble, etc. (carbonates). 
We know it in three allotropic states : — 

1. Diamond. 

2. Graphite (plumbago, black lead). 

3. Amorphous Carbon (uncrystallized). 

Graphite, mixed with a little Sb and S, is used to make 
common "lead pencils." Mixed with clay, it makes cru- 
cibles, the most refractory (difficult to melt) known. Stove 
polish and lubricating material are made of it. 

Amorphous Carbon (more or less impure) includes 
charcoal, mineral coal (the remains of vegetation of the 
carboniferous age), coke, peat, animal charcoal (bone 
black), soot, lamp-black, and gas-carbon. 

Note. — For fuller description of the above and of all such substances 
briefly mentioned in this primary work, see the dictionary and cyclopae- 
dia. Every High School should have an unabridged dictionary and a 
cyclopedia placed ivhere scholars can readily refer to them. 



64 



CHEMICAL PRIMER. 




Fig. 24.— Mercuric Tub. 



Carbon for a long time resists decay. Fence posts are 
charred to preserve them. Neither acids (except nitric) 
nor alkalies affect it. 

Exp. 47. —Collect in 
test-tube over mercury 
(or by displacement of 
air) H 3 N. Introduce 
into the gas a piece of 
fresh burned, dry char- 
coal, which will float on 
the heavy liquid, and 
quickly dip the mouth 
| of test-tube beneath mer- 
cury. The Hg rises in 
test-tube, because C ab- 
sorbs the H 3 N in its 
pores. 

Note. — Chisel out of hard wood a trough 5 inches long, 1 inch wide, 
and 1 inch deep. Nail a lead post to one or both ends to support small 
test-tube. This makes awery good mercuric pneumatic tub, but the 
mercury must not come in contact with the lead. [Wooden supports 
are better for permanent use.] Use narrow test-tubes and keep 
them from the side of the tub, else the air creeps in. 

Carbon absorbs many times its bulk of gases, condens- 
ing them in its pores. Fresh burned charcoal is a good 
" disinfectant " for foul gases. They are destroyed 
within its pores by the absorbed O ; i. e. y by oxidation (so 
that C is not a disinfectant in a strict chemical sense, but 
its action is mechanical). O is the real disinfectant. 

Exp. 48. — Finely pulverize charcoal by rubbing two sticks together, 
or, if animal charcoal is used, by grinding in mortar, and place upon 
filter. Slowly moisten with distilled water. Let diluted ink (or indigo 
solution, vinegar, etc.) fall drop by drop upon the charcoal from an 
ordinary paper filter above it. The filtrate from charcoal is colorless. 

Charcoal is a good decolorizing agent. Animal char- 
coal is largely used in sugar refineries to remove soluble 
impurities and color. 



CARBON. 



G5 



Exp. 49. — Heat upon platinum foil a piece of sugar (or other organic 
matter, as tartaric acid, flesh or vegetable). It chars (turns black, as the 
more volatile constituents are driven off, leaving the carbon free). 

Charring is a good test for carbon (or for organic mat- 
ter) 

Exp. 50. — Upon charcoal put a little litharge (Pb 0). Heat in the 
blow-pipe flame. The O is taken by the C leaving the Pb free (uncom- 

bined). S 

2PbO + C = Pb, + C0 2 

metallic 
lead 

Carbon is a good deoxidizing or reducing agent. 

Heated with the oxides of most metals it deoxidizes them, 
and is thus of special use in reducing ores that are oxides 
(or carbonates, since great heat breaks up the carbonate 
grouping, setting C 2 free, and leaving an oxide behind). 



Exp. 51. — Upon pieces of marble (Ca C0 3 ) in a flask, pour dilute (20 
per cent. ) H CI. Collect gas by displacement of air. 

Reaction (class 4): Ca C0 3 + 2 H CI = Ca Cl 2 + H 2 + C 2 

carbonate acid salt water carbonic 

oxide 




Fig. 25. 



66 CHEMICAL PRIMER. 



Carbon dioxide (carbonic oxide, carbonic anhydride, 
old name carbonic acid) is a colorless gas, with slightly 
acid taste. It is much heavier than the air (sp. gv. 1.5, 
with H as standard 22) in which it exists free,- forming 
about i o^o o by volume. 

Exp. 52. — Into a jar of C 2 introduce a lighted taper. It is extin- 
guished. 

Exp. 53. — Arrange short lighted candles along an inclined (not too 
steep, else draft is produced) trough (piece of gutter). Pour a large 
receiver of C 2 into the top of the trough. The candles go out in order 
as C 2 reaches them. 

Exp. 54. — Put a mouse into a receiver of C 2 . The animal dies. 

Carbon dioxide does not support combustion and is 

not inflammable. Though not poisonous in a strict 
sense of the word, yet animals die from suffocation in air 
containing about five per cent, of the gas. It hinders 
the elimination of the same gas, C 2 from the lungs (but 
see C 2 in appendix). 

Exp. 55. — Burn Mg ribbon in a jar of C 2 . Black particles of carbon 
appear mixed with the white oxide. 

CO, + Mg, = 2MgO + C 

white black 

Dissolve oxide in dilute HN0 3 and C is made more distinct. C 2 
supports the combustion of magnesium, but by a supporter of combus- 
tion i i general we mean a substance that supports the combustion of 
hydrocarbons. 

Exp. 56.— Repeat Exp. 33. 

Lime-water is the test for C 2 . No other gas will (1) 
extinguish flame and (2) render lime-water milky. 

Exp. 57. — Hold the breath a short time and then expel the air into a 
receiver. Test. It extinguishes the flame of taper and turns lime-water, 
shaken up in the receiver, milky. 



CARBON, 



67 




Animals exhale C 2 from the 
lungs as a waste product. They 
use up O from the air and replace 
it by C 2 . 

Exr. 58. — Place a small branch having 
numerous and fresh leaves in a tall receiver 
(prepared as in Fig. 26) of spring or brook 
water (>'. e. , water that has been sufficiently 
exposed to carry much air dissolved) and 
place apparatus a few hours in direct sun- 
shine. O is evolved and, together with a i ^' 
little N and traces of C 2 driven off by the sun's heat (of course a 
little is also driven off by sun's heat), collects in top of receiver. Test 
by very slender and glowing taper. The gas is found to be principally 
oxygen. 

Plants in sunshine exhale through their leaves O (except 
certain low orders), using up C G 2 of the air and building 
the C into their tissues. The leaves of plants are often 
compared to the lungs of animals, except we must 
remember that the process is reverse. They receive the 
air through little stomata (mouths) on the under side (prin- 
cipally). But in some important respects the leaves cor- 
respond to the digestive organs of animals (including 
glands preparing chyle for the general circulation, viz., 
" mesenteric glands" and the liver). The plant gets vastly 
more food (by weight) from the air than from the richest 
soil. The smaller portion which it gets from the soil is, 
however, an essential portion, and it will not flourish in 
poor soil. 

Plants purify the air for animals, and animals by a 
reverse process supply from their own waste the needed 
elements of plant food. Carbon dioxide is also formed in 
large quantities by the decay of organic matter. The 
proportion, however, of C (X in the air remains practi- 
cally the same from year to year. 



6 8 CHEMICAL PRIMER. 



C 2 tends to collect in old wells and in unventilated portions of 
mines. It is called by miners choke-damp. Wherever a light is ex- 
tinguished by C 2 , it is unsafe to go. 

Exp. 59. — Place a short lighted candle on a rubber cork and intro- 
duce it into the bottom of a vertical glass tube, which the cork tits. 
The candle goes out. In the tube suspend a smaller tube and introduce 
the lighted candle as before. It burns steadily. The heated air (and 
C 2 ) rises in the small tube (upward draft) and the fresh air containing 
falls between it and the larger tube. 

Two openings, at least, are necessary for proper ventilation. In 
mines where it is possible, two shafts, one at each end, with a fire at 
the base of either, answers the purpose. Very complex arrangements, 
however, have to be made in many cases to force air into the various 
parts of large mines. Plenty of fresh air is the only preventive to keep 
fire-damp (marsh gis C HJ and C 2 from accumulating in dangerous 
quantities. 

Exp. 60. — Hold the breath a short time and then expel it into a jar 
and close by rubber cork. Set aside in a warm place for a day or two 
and then open. A very offensive, putrescent odor greets the sweetest- 
breathed experimenter. (C 2 has no odor.) [This experiment may, 
perhaps, best be performed at home.] 

Churches, school-rooms, bedrooms, etc., should be very 
thoroughly ventilated, not so much to free them from the 
injurious C 2 as to remove the poisonous "animal 
vapor" (moisture in suspension) thrown off from the lungs. 
This " vapor " holds all manner of organic impurities in 
solution. 

Exp. 61. — Fill a narrow, deep test-tube with C 2 . Close with the 
thumb and open under cold water (but previously boiled), pressing the 
mouth a few inches below the surface. Close the test-tube, remove and 
shake. Part of the C 2 dissolves. Open under water and repeat shak- 
ing. In this way the test-tube of C 2 may be dissolved in a test-tube 
of water. 

Water at 15° dissolves one vol. of C 2 , but if the gas is under press- 
ure, it dissolves much more (by weight). 



CARBON. 



G9 



"Soda Water" is nothing but a ^solution of C 0. 2 under 
pressure in water. It probably receives ics inappropriate 
name because of its effervescence when relieved of pressure 
(like sodium carbonate, "soda," when mixed with an acid). 

C 2 has hjen condensed to a liquid, and by rapid evaporation of a 
part, the rest is solidified (frozen), forming a snow-white solid. This 
solid is so coid that when touched it produces the same effect as red- 
hot iron (see similar condensation of S 2 , appendix). 

As we have seen, C 2 and H 2 
are the two great products of ordi- 
nary combustion. The chemistry 
of a burning candle is in a general 
sense very simple. The wick is first 
raised to the igniting point, the 
heat melts the tallow (composed 
chiefly of H and C combined), and 
the liquid is then drawn up by cap- 
illary attraction into the wick. Here 
the great heat changes the liquid 
tallow into the gaseous state (with 
decomposition into various hydro- 
carbons). Flame is burning gas. 
The flame is hollow, as no O can 
penetrate to its center, and the hol- 
low is filled with the unburnt gases. 
(These may be drawn away hy a 
fine glass tube and burned at its end, if the candle is a 
large one.) In floating outward, the C from the decom- 
posed hydrocarbons becomes white hot and gives out light, 
but soon meets the O of the air and becomes C 2 at the 
instant it ceases to give light. Outside is a faintly blue 
" mantle" with excess of 0, and at base blue cup of burn- 
ing H and CO. If a cold piece of glass or porcelain is in- 




Fig\ 27. 



70 



CHEMICAL PRIMER. 



troducec! into the flame, the C is lowered below the ignit- 
ing point and is deposited as smut. The H 2 (steam) is 
condensed and deposited also. We notice this condensed 
steam upon the cold chimney when the lamp is first 
lighted, but it evaporates as the chimney becomes hot. 

Illuminating gas is made from bituminous coal by heating in retorts 
and collecting volatile hydrocarbons in a holder. It contains various 
gases, H, C 0, C H 4 (marsh gas, "fire damp" of miners), C 2 H 4 (defi- 
ant gas, ethylene), C 6 H 6 (vapor of benzol), etc., and (before purifica- 
tion) others that must be removed, as H 3 N, C 2 , H 2 S (and other sul- 
phur compounds), besides vapor of "tar." Tar is a very complex sub- 
stance, from which the aniline dyes, carbolic acid, etc., are obtained. 
H 3 N may be removed by passing through water (or H CI, old method), 
C 2 by passing through "pans" of lime (Ca 0), and the sulphur com- 
pounds by passing over ferric hydrate. The last reaction may be rep- 
resented thus: — 



Fe 2 6 H + H 2 S 

fon-lo hydrogen 

sulphide 




2 Fe 2 H O 

ferrous 
hydrate 



+ 



+ 



S 

free 
sulphur 



On exposure to the air, ferrous 
hydrate becomes ferric hydrate, and 
the material may be repeatedly used 
till the free sulphur forms from 40 to 
50 per cent. The tar vapor condenses 
and runs into the "tar well." The 
refuse (coke) is left behind in the 
retorts, also adhering " gas carbon." 

The purified gas is measured by 
the meter and passes into the holder, 
from which it is distributed to con- 
Fig. 28.— Section of Gas Meter. sumers. Illuminating gas is also 

The three arrows represent the rota- mac [ e f rom crude petroleum, more 
tion of the chambers; the solitary arrow J ; 

the escape of the gas from chamber, complex machinery being used. 
Gas enters through the U-shaped center. 

Bunsen's Burner is represented in Fig. 21 and is used when heat, 
not light, is wanted. The gas is mixed with the air, drawn in through 
openings at the side. The flame is condensed, is much hotter, and does, 
not smut cold glass. 



CARBON 



71 



Exr. G2. — Heat in ex- 
treme tip of blowpipe flame 
the end of a clean coppei 
wire. It turns black, i. c, 
is oxidized, forming Cu 
Heat in the midst of flam e 
nearer the blowpipe. The 
Cu is reduced (deoxi- 
dized) and the bright me- 
tallic copper appears. 




Fiy. 29. 



By means of the biowpipe we may do two things, 
oxidize most metals (a very small portion is sufficient for 
tests) and reduce their oxides. 

At A (Fig. 29) a substance may be oxidized, because here we have ara 
excess of thrown forward from the blowpipe and highly heated, The 
flame in the center at B is reducing, for here there is an excess of highly 
heated carbon. The reducing flame is best produced by holding the noz- 
zle of blowpipe a very short distance from the flame instead of in it. 
The blowpipe is a very valuable instrument in the analysis of oreSa 

Exp. 63o — Two inches above a gas burner hold a fine wire gauze and 
ignite jet of gas above the gauze. It burns above, but not below. The 
wire being a good conductor of heat reduces the gas below the igniting 
point, and the flame cannot pass through the gauze. 

Davy's Safety Lamp used by miners is 
essentially a lamp surrounded by a wire 
gauze. The flame cannot pass through 
this to ignite the "fire-damp" (C H 4 marsh 
gas). This dangerous gas explodes vio- 
lently when mixed with air and ignited 



Exp. 6 4- — Into a flask put a small quan- 
tity of oxalic acid crystals and cover with 
strong sulphuric acid. Heat gently and 
pass gases through wash bottle containing 
strong solution of K HO. Collect over 
water. 

H 2 C A = H 2 + C 2 + C O 




Fig. 30.— Wash Bottle, 



72 CHEMICAL PRIMER, 

The sulphuric acid absorbs H 2 from the oxalic acid, breaking up the 
molecule. The K 11 solution absorbs the C 2 , becoming K 2 C 3 (and 
H 2 0), and the C is collected in receiver. Test by lighted taper. It 
burns with bluish flame 

Carbon monoxide C O (carbonous oxide, old name car- 
bonic oxide) is a colorless poisonous gas formed by burn- 
ing C in a close atmosphere. Escaping from hot stoves 
through the pores of the iron into ill-ventilated rooms, it 
causes headache. In large quantities it speedily produces 
coma and death. Its pale, lambent flame is frequently 
seen when fresh hard coal is placed upon the grate. 

Note. — Organic chemistry may be considered as carbon continued. 
The previous rules for writing formulas and names, which hold so gen- 
erally in inorganic chemistry, fail in numberless instances to meet the 
requirements of organic chemistry, as we shall see. Notice that the 
order of C H and O is usually used in organic chemistry instead of HC 
and 0. (See marsh gas, vapor of benzol, etc., above, and also Organic 
Chemistry. ) 



CHAPTER XXII, 



BINARY ACID- AND SALT-FORMERS, 

FLUORINE, CHLORINE, BROMINE, IODINE, AND CYANOGEN. 

Exp. 65. — Into a small flask on a sand-bath, put equal weights of 
common salt and manganese dioxide, well mixed. Add sufficient water 
to make thin paste. Pour in through funnel a small quantity of sul 
imuric acid (commercial) and collect gas in large test-tube over hot 
water, or by displacement of air in deep receivers. Heat should he 
applied to A ask to drive off the last (and greater portion) of the gas. A 
c ouble reaction takes place: — 

(1)— H 2 S 0, + 2 Na CI = Na 2 S 0, + 2 H CI 

(2)— Mn 0, + 4 H CI = Mn Cl 2 + 2 H 2 -f- Cl 2 



BINAR Y A CID- AND SALT- FORMERS. 73 



The gas may be freed from H CI by passing through wash bottle (see 
Fig. 30) of cold water . It may be dried, if desired, by passing through 
strong H 2 S 4 in the same manner, and then collected by displacement 
of air. 

Cailtioilo — Care should be taken not to breathe (except in minute 
quantities) chlorine, cyanogen, or, in short, any gases or products that 
are poisonous. Small quantities of such gases should be used in experi- 
ments. If larger quantities are desired, they should be made under a 
"gas chimney," or near a window with outward draft. 

Chlorine is a greenish-yellow, poisonous gas of a suffo- 
cating odor. When very dilute it produces coughing 
(relieved by inhaling dilute ammonia), and breathed in 
larger quantities, inflammation of the trachea and bron- 
chial tubes. It is 2*5 times heavier than air. It is an 
abundant element, but is not found free in nature. 




Exp, 66.— Burn a jet of H 
in CI and test product by blue 
litmus, (Fig. 31.) 



H + 01 = 



HC1 



Fig. 31. 



Exp, 67.— Into a jar of CI 
plunge a small lighted pitch- 
wood taper. It burns awhile 
with red, smoky flame, but 
soon goes out. The CI unites 
with H of the taper, setting the 
C free as smoke. Test by blue 
litmus. 



CI has a great affinity for H. Upon this affinity de- 
pends its value as a disinfectant. H is an essential con- 
stituent of many foul gases CI destroys them as it 
destroys coloring matters. (See Exp. 72.) 

Exp. 68. — Upon paper containing printer's ink write with common 
ink (iron tannate Fe 3 2 C 27 H 19 17 ) and lower into a jar of CL The com- 
mon ink is bleached, but the printer's ink (linseed oil and lamp-black , 
C) is unaffected 



74 CHEMICAL PRIMER, 

Exp. 69. — Into a black bottle containing cold water pass CI gas (puri- 
fied of H CI). The CI dissolves (3 vols.) and forms "chlorine water." 
Set aside as a reagent. 

Exp. 70. — Expose a little chlorine water in a beaker to the sunlight 
for a few hours. Place it beside a beaker of fresh chlorine water from 
dark bottle, and to each add a piece of blue litmus paper. The fresh 
chlorine water bleaches, the other turns the litmus red. The light en- 
abled the CI to decompose the water thus: — 

Cl 2 + H 2 = 2HC1 + O 

("Light favors chemical change. 95 } 

Exp. 71. — Into a beaker containing CI water let fall a few drops of 
red ink (cochineal), or indigo solution, aniline purple, etc. The color is 
discharged. 

Exp, 72. — Into a beaker of chlorine water introduce a piece of calico. 
The color is discharged, except from those portions colored by mineral 
substances, 

Chlorine is a powerful bleaching agent, and for this 
purpose is largely used in the arts. It bleaches (and dis- 
infects) in two ways : — 

1. By removing H from the substance- 

2. By removing H from water, setting free "nascent" 0, which 
bleaches. (Thus CI bleaches by proxy. ) Dry CI does not bleach. 

Bleaching powder, "chloride of lime," is mixture of calcium hypo- 
chlorite (Ca 2 CI 0) and calcium chloride (Ca Cl 2 ). A dilute acid sets 
chlorine free with promptness. Moisture and exposure sets chlorine 
free slowly, therefore bleaching powder is used as a disinfectant. Acids 
set the chlorine free rapidly. CI may be conveniently prepared from 
bleaching powder. 

Exp. 73. — Into a jar of CI sprinkle antimony (powdered with a file). 
It takes fire and fills the jar with white fumes. (Sb Cl 5 , poisonous.) 

Exp. 74. — Burn Mg ribbon in jar of CI, igniting it first in alcohol 
or Bunsen's flame, 

CI has a great affinity for the metals, (Sb is semi-metal.) 
Most of them burn in chlorine, forming chlorides. Chlo- 
rine, as we have seen, does not unite with carbon and 



BINARY ACID- AND SALT-FORMERS. 75 

therefore does not support the combustion of hydrocar- 
bons. 

Exp. 75. — Into a test-tube containing a little common salt, pour strong 
sulphuric acid, and gently heat. Collect gas in narrow, deep test-tube 
by displacement of air (holding mouth upward). 

y 

2 Na CI + H 2 S 4 = Na 2 S 4 + 2 H CI 

Cover test-tube with thumb and open under water; the water rushes 
in violently and fills the tube. 

Hydrochloric acid (hydrogen chloride, chlorohydric 
acid, muriatic acid) is a colorless, irrespirable, acid gas, 
very soluble in water (450 vols, in one at 15°). The 
liquid called hydrochloric acid is really a solution of the 
gas in water (a mere solution). 

Exp. 76. — Dip a glass rod into strong ammonia water, and another 
into strong H CI and bring the rods together. Dense white fumes of 
ammonium chloride appear. The reaction is: — 

H 4 K H + H CI = H*N" CI + H 2 
or omitting the water 

H 3 N + H CI = H 4 N CI 

This is a rough test for H CI or iorfree ammonia. 

Exp. 77. — Boil in H CI a small piece of gold-leaf. It does not dis- 
solve. Add a drop of HN 3 , a yellow solution of gold chloride (AuCl 3 ) 
appears. 

Hydrochloric acid and nitric acid form aqua regia, the 

solvent of gold. 

Exp. 78. — Repeat Exp. 6 and 7, and also use other soluble chlorides. 
Soluble chlorides precipitate silver as silver chloride. 

Exp. 79. — Heat a little pulverized K CI 3 upon charcoal in the blow- 
pipe flame. The coal burns explosively. 

s 

2 K CI 3 + C 3 = 2 K CI + 3 C 2 
The chlorates, as well as the nitrates, are good oxidiz- 
ing agents. Potassium chlorate is one of the most impor- 
tant of the chlorates. 



76 CHEMICAL PRIMER. 

Exp. 80. — In a test-tube thoroughly mix a little pulverized K Br and 
Mn 2 , moisten with water, add strong H 2 S 4 , quickly close by perfo- 
rated rubber cork and collect liquid in deep test-tube cooled in water. 
(Exp. 39.) Heat to drive off the larger portion of the bromine. Pour 
into glass- stoppered bottle and preserve. 

(1)— H 2 S0 4 + 2KBr = K 2 S 0, + 2 H Br 
(2)~Mn0 2 + 4HBr = Mn Br 2 + 2 H 2 + Br 2 

Bromine is a volatile, poisonous, dark red liquid, very 
similar in its properties to chlorine, but less active. 

Many experiments analogous to those under CI may be performed 
with bromine vapor. Thus, Br bleaches and unites with H to form 
hydrobromic acid. H Br and other soluble bromides precipitate silver 
as yellow silver bromide, which blackens in sunlight like silver chloride. 
(Perforin experiments and write reactions.) Br is not a very abundant 
element. Potassium bromide is used in medicine to repress excessive 
reflex action (nervousness, hysterics, etc.). 

Exp. 81. — Into a test-tube put solution of K Br and add a drop or 
two of chlorine water. 

Reaction: K Br + CI = K CI + Br (free) 

The solution becomes yellow. Bromine water is yellow. 

This experiment shows the superior ckeillism (chemical affinity) 

or activity of chlorine and a method of testing for bromides. Notice 
that the " strength " of Br is the same as that of CI ; that is, both are 
monads. 



Exp. 82. — In a deep test-tube place pulverized K I and Mn 2 well 
mixed. Moisten, and adding strong H 2 S 4 , gently heat. Violet colored 
vapor of iodine appears. Set aside for a few moments. Iodine con- 
denses on the sides of the test-tube. 

Iodine is a grayish-black solid with metallic luster. 
It is a comparatively rare element. 

Exp. 83. — To tincture (solution in alcohol) of iodine very dilute (with 
water), add dilute solution of starch paste. Blue iodide of starch 
appears. [That the compound is not a very stable one may be shown 
by gently heating. The blue color disappears, but reappears as the 
solution cools.] 



B1XARY ACID- AND SALT FORMERS. 77 



Exp. 84. — Boil a small piece of potato in beaker of water. Filter, 
and, after filtrate is cold, add a few drops of very dilute iodine tincture. 
Blue iodide of starch appears. 

Starch is a very delicate test for free iodine, and, vice 
Vi rsa, iodine for starch. (See Exp. 85.) 

Soluble iodides precipitate silver as silver iodide, which blackens in 
sunlight. Iodine was formerly much used in medicine to "scatter" 
glandular swellings, etc. It is now less often used. 

Exp. 85. — Into a test-tube put solution of K I. Add two or three 
drops of starch solution. Xo blue color appears, because the I is com- 
bined with K. Add a few drops of chlorine water. The blue color 
appears because the CI unites with the K setting the I free. 
K I + CI = K CI + I (free) 

The free I then unites with the starch, forming the blue color. 

This experiment shows the superior chemical affinity of chlorine and 

a method of testing for iodides. The " strength" of CI is no greater 

than that of I. 

•— 

Fluorine is the only element which does not unite 

chemically with oxygen. It is supposed to be a colorless 

gas, but so great is its chemical affinity that it has not 

been satisfactorily isolated (set free). 

Exp. 86. — In a platinum or lead crucible place two grams of pulver- 
ized Fluor Spar (Ca F 2 ) and cover with strong ELS 4 . Coat a piece of 
glass at a gentle heat with paraffine (or wax) and having written a word 
upon the paraffine, gently heat crucible, and removing lamp, cover with 
glass. The word is etched upon the glass. (Caution, Exp. 65.) 

(1)— CaF 2 + H 2 S0 4 = CaSO, + 2HF 

(2)— 4 H F + Si 2 = 2 H 2 + Si F 4 

of the 
glass (which see) 

Hydrofluoric acid (H F) is used for etching letters or 
designs upon glass. If the gas is used, the letters or de- 
signs are left rough ■ but if a solution of the gas in water 
(kept in gutta percha bottles) is used, the etched portion 
is smooth. 



78 CHEMICAL PRIMER. 

Exp. 87. — In a tube of hard glass place a small quantity of mercuric 
cyanide (Hg 2 C N). Heat carefully to dull redness and collect gas in 
test-tube over mercury. Test by lighted taper. The gas burns with 
beautiful reddish-purple flame. (Caution, Exp. 65.) 

S 

(l)-H g 2CN = Hg + (CN) 2 * 

/ S 

(2 )_c]sr + o 2 = co 2 + n 

Cyanogen (C N or Cy) is a colorless, pungent, inflam- 
mable gas with strong peach-blossom odor. As the mol- 
ecule of hydrogen has been represented thus | H H | , so 
the molecule of free cyanogen may be represented thus 
ICNU ITI or C 2 N 2 . * 



It is interesting as being the first "compound radical' 9 isolated. 
It forms binary salts, several of which are very important. The 
intensely poisonous "prussic" acid (hydro-cyanic acid, HCN) may be 
formed by the action of sulphuric acid on potassium cyanide. (Do not 
'perform the experiment. ) 

2KCN + H 2 S 4 = K 2 S 4 + 2 H C N 

Prussic acid is used in medicine. Many patent medicines claiming to 
be preparations from cherry bark are essentially nothing but very dilute 
solutions of hydro-cyanic acid. Potassium cyanide is one of the most 
important of the cyanides. It is very poisonous. 

MISCELLANEOUS QUESTIONS. 

1. Give thrjgjjiifferent methods of making 0. 

2. How many litres of can be made from 150 grams of K CI 3 ? 
[Note.— A litre of H weighs .0896 grams (at 0° and barometer 760 
mm), and a litre of weighs 16 times as much, a litre of N 14 times as 
much, etc., according to the atomic weight of the gas. To find the weight 
of compound gases, multiply the iceight of H by one-half the molecular 
weight of the gas. Ex. — A litre of C 2 weighs 22 times .0896 gms.] 

3. Tell what you know about O (ten lines). 

4. Give experiments proving the character (properties) of O. 

5. Reaction in making H? 

6. How many litres of H could be made by using 5 grams of Zn? 

7. How many grams of Zn must be used to make 15 litres of H? 



SULPHUR AND PHOSPHORUS. 79 



8. Give properties of H and prove by detailing experiments. 

9. What is a deliquescent salt? An efflorescent salt? 

10. How was N obtained ? 

11. Give the composition of air, 

12. What was proved by the "ammonia fountain"? 

13. What is "aqua regia"? and why so called? 

14. What is meant by "nascent" hydrogen? 

15. Give experiment proving that C is a good decolorizing agent. 

16. Give experiment showing that fresh burned C is good "disinfect- 
ant " 

17. How may C 2 be made? 

18. Fifty litres of C 2 could be made by using what quantity (grams) 
of Mg C 3 ? 

19. Detail three experiments under carbonic oxide 3 

20. Animals and the higher orders of plants differ with respect to use 
of C 2 and 0. How? 

21. Write 5 lines about chlorine, saying the most possible. 

22. How is glass etched ? Copper and iron ? 

23. What is cyanogen? Why is it treated in the chapter on chlorine, 
bromine, etc., rather than under nitrogen or carbon? 

24. What is the specific gravity of hydrochloric acid gas ? Is it 
lighter or heavier than air ? 

25. When " marsh gas " burns, what are the products ? When H 2 S 
burns ? 

CHAPTER XXIII. 



SULPHUR AND PHOSPHORUS. 

Sulphur is found free (native) in volcanic regions. It 
is found combined in cinnabar (Hg S), iron pyrites (Fe S a 
iron clisulphide), galena (Pb S), blende (Zn S), etc. It is 
contained in most animal tissues and especially in the 
perspiration and hair, also in many vegetables, especially 
in those that are strong-smelling. 



80 



CHEMICAL PRIMER. 



Exp. 88. — Place a drop of water upon a well- cleaned silver coin, 
and upon it place white of boiled egg. Leave over night. The coin 
is blackened. 

Eggs contain sulphur and so tarnish silver spoons, black silver sulphide 
(Ag 2 S) being formed. Sulphur has great chemical affinity for Ag. 

Exp. 89. — Into a strong solution of lead acetate introduce white 
horse-hairs, and heat to hasten reaction. They turn dark 

Many "hair dyes" contain salts of lead. The metal unites with S of 
the hair, forming black Pb S. Such hair dyes are highly injurious. 

Sulphur exists in several allotropic ('physically different) states, among 
which are (1) the ciwstallized, (2) the common uncrystallized ("amor- 
phous"), and (3) the plastic (viscid, also uncrystallized). 

ExPo 90.— Heat a small quantity of sulphur for about five minutes, or 
till the thin, light- colored melted mass, after becoming dark and thick, 
becomes thin again. Pour by thin stream into cold water. Plastic S 
results. This form is unstable and becomes brittle in a day or two, as 



id 




specimen the next mornings 

Exp. 91. — In a small glass tube 
closed at one end (by fusing tip in 
flame of Bunsen's burner) place small 
piece of iron pyrites (Fe S 2 ) and heat 
slowly so as not to crack the fused end 
of tube. Part of the sulphur sublimes 
and condenses on cold part of the 
tube. 

3FeS 2 = Fe 3 S, + S 2 

Note. — A substance sublimes when, on applying heat, it rises as a 
vapor and condenses as a solid. A substance distills when it rises as 
a vapor and condenses as a liquid. 

S may be obtained from iron pyrites by "roasting" the 
ore and condensing the S. The principal supply, how- 
ever, comes from the volcanic regions of Italy. (See 
Exp. 93.) 



Exp. 92. — Repeat Exp. 4, placing in the bottle a red rose. 

is slowly bleached. 



The rose 



SULPHUR AND PHOSPHORUS. 81 



Sulphur dioxide is used in bleaching silk, straw, and 
woolen goods, which would be injured (turned yellow) by 
chlorine. Colorless compounds are formed by the union 
of the S 2 with the coloring matter, but the reaction is 
too complex to be written out. 

S 2 is a good antiseptic. 8 burned in a vessel prevents 
the fermentation of the liquid (as new cider) afterwards 
put in. Like all strong antiseptics it is poisonous. It is 
also a valuable disinfectant. 

Exp. 93. — Burn S in a large, clean flask and pass into it H 2 S. (See 
Exp. 8. ) Let stand a few hours — the bottom and sides of the flask are 
covered with a thin white coat of sulphur. [S looks white when in thin 
deposit. ] 

S0 2 + 2H,S = S 3 + 2H 2 

This illustrates the formation of native sulphur in vol- 
canic regions, as volcanic gases contain S 2 and H 2 S. 



Exp. 94. — Burn S as in Exp. 4, and quickly stir with glass rod, upon 
the end of which is twine wet with strong H JN" 3 . (Nitrates are good 
oxidizing agents, we have learned.) The S 2 takes from the nitric 
acid, becoming S 3 sulphuric oxide (anhydride). Shake up with 
water. 

S 3 + H 2 — H 2 S 4 (dilute) 

Test water with barium chloride, the test of sulphuric acid (and solu- 
ble sulphates). 

H 2 S0 4 + BaCl 2 = BaSO, + 2 H CI 

white precipitate 

Sulphuric acid ("oil of vitriol") is a colorless (if pure) 
oily liquid (sp. gr. 1.84). It is the most important of the 
acids, and is used in preparing numberless other sub- 
stances, especially acids. 

The experiment illustrates its preparation. 



82 CHEMICAL PRIMER. 

S 2 from burning sulphur is carried into large leaden chambers, 
whose floors are covered with water. Into these air and nitric acid 
fumes are admitted. The N from the nitric acid acts as a carrier of 
from the air to the S 2 . (See Exp. 38.) 

s s 

2S0 2 + N 2 4 = 2S0 3 +2NO 

y 

2NO + 2 = NA 

from 
the air 

The dilute acid is evaporated in leaden pans, till it begins to attack 
the lead. (Commercial H 2 S O i contains Pb S 4 , which falls as white 
precipitate when the acid is diluted.) It is then removed and concen- 
trated in glass or platinum stills. 

Exp. 95. — Into a beaker containing water pour twice its volume of 
strong H 2 S 4 . Great heat is developed. 

Exp. 96. — Upon white sugar (C 12 H 22 O u ) (starch or wood C 6 H 10 O 5 ) 
pour strong sulphuric acid. It chars by removing the elements of water, 
leaving the black carbon free. — Evaporate dilute H 2 S 4 upon white 
paper. As the acid increases in strength, the paper chars. 

Concentrated sulphuric acid has a great affinity for 
water. It is used for drying gases with which it does not 
react. Care must be taken in diluting the acid, to mix 
in a vessel that will stand the heat. (In dilating heavy 
liquids, pour the liquid into the water, not water into the 
liquid.) "Fuming sulphuric acid" is a solution of S 3 
in H 2 S 4 . 



Exp. 97. — Into a solution (slightly acidulated with H CI) of salts of 
lead, copper, bismuth, mercury (ic), arsenicum, antimony, and tin 
respectively in test-tubes, put solution of H 2 S. Reaction by change of 
partners throws down sulphides. Pb S black, Cu S black, Bi 2 S 3 black, 
Hg S white, yellow, reddish-brown, and finally black, As 2 S 3 lemon 
yellow, Sb 2 S 3 orange, Sn S brownish-black, Sn S 2 yellow. 

Hydrogen sulphide (H 2 S " sulphuretted hydrogen") is 
much used in the laboratory to precipitate metals, as sul- 
phides. (See Analytical Charts.) H 2 S is readily in- 
flammable, as may be shown by igniting in test-tube. 



SULPHUR AND PHOSPHORUS. 83 

Note. — Hydrogen sulphide has a slight acid reaction and was called 
by the old chemists hydrosulphuric acid. It unites with many of the 
bases to form sulphides, and these sulphides might be classed as binary 
salts. For reasons which need not be explained here, chemists do not 
now class sulphides in this way, but consider them as analogous to 
oxides. 

Carbon disulphide (C S 2 ), a volatile, colorless, inflam- 
mable liquid, may be produced by passing sulphur over 
red-hot coals. It is an excellent solvent, dissolving readily 
S, P, I, and many organic substances. It refracts light 

powerfully, and hence is often used in filling prisms. The 
impure disulphide (its heavy vapor) is used to poison 
squirrels, insects, etc. 

The rare element, selenium, in many respects resembles sulphur. 
We have the compounds H 2 Se, Se 2 , H 2 Se O i5 etc. (See Sulph- and 
Selen-Salts.) 



Phosphorus is a semi-transparent, nearly colorless, 
wax-like solid. It is kept under water in "sticks," as it 
slowly oxidizes in the air and takes fire at a very low 
temperature. It is highly poisonous. Its vapor breathed 
(in more than minute quantities) produces ulceration of 
the jaw, cured with difficulty. (See Caution, Exp. 24.) 

Another variety, red or amorphous, is known. This differs widely 
from ordinary P. It does not emit the "jaw-poisoning fumes" and can 
be safely handled. P in this "allotropic" state maybe prepared by 
heating ordinary phosphorus in a closed vessel. Part of the P used in 
making N (Exp. 35) is changed into the red variety. 

Phosphorus, because of its low igniting point, is largely 
used in the manufacture of matches. The wood of the 
match is first dipped in melted sulphur, then into paste 
of P, potassium nitrate (or chlorate) for an oxidizing 



84 



CHEMICAL PRIMER. 



agent and glue (varnish). The P is kindling for the S, 
the S for the wood (hydrocarbon), while the nitrate fur- 
nishes the O for rapid combustion. The reactions in 
burning a match are: — 

P 2 + 6 = P 2 5 ; S + O, = S0 2 ; 

H 2 + O = H 2 0; C + 2 = C0 2 . 

" Safety Matches" contain no P, and ignite readily only when the 
chemicals of the match are rubbed on a surface of red phosphorus (and 
powdered glass to increase friction). 

Phosphorus glows in the dark (its best test). (See Appendix.) Such 
glowing without heat is called phosphorescence, but not by any 
means is all so-called "phosphorescence" produced by phosphorus. 

Exp. 98. — Into a test-tube half full of water drop 
j several very small pieces of P. Cover P with fine 
crystals of K CI 3 (oxidizing agent). By means 
of a pipette (glass tube) take up a little strong 
H 2 S O i5 and, introducing the tube into the water 
as deep as the K CI 3 (Fig. 33), open, letting the 
strong acid upon the chlorate. The P burns be- 
neath the water. 

A combustible element burns if raised to the 
j igniting point in presence of free oxygen, or of an 
ssssasssssssissssssyf oxidizing agent. (In this case C1 2 4 from the 
ri &- S3 - reaction.) 

Calcium phosphate (Ca 3 2 P OJ forms fully one-half by weight of 
bones, and is the source of P. "Superphosphate of lime" is a peculiar 
acid phosphate of calcium (Ca H^ 2 P 4 ). 




BORON AND SILICON 85 



CHAPTER XXIV. 



BORON AND SILICON. 

Boron may be obtained from boron oxide B 2 3 as a broivnpoivder, and 
also in yellowish-brown crystals. Boracic acid, or boric acid (H 3 B 3 ), 
is found in the lagoons of the volcanic regions of Tuscany. Jets of 
steam containing the acid issue from the earth and are absorbed by the 
water. This is afterward evaporated by heat from the jets, leaving the 
crystallized acid. Boracic acid is also made from borax. 

Exp. 99. — Upon copper (or iron) wire covered with a coating of the 
black oxide, melt a borax bead. The melted borax dissolves the oxide, 
leaving the bright "metallic" copper (or iron). 

Borax (sodium tetraborate, Na. 2 B 4 7 , 10H 2 O) is used 
in welding and soldering, because when melted it dissolves 
the oxide of the metal, leaving the surfaces bright. It does 
not deoxidize metals, but forms borates. (See Hard Water.) 

Exp. 100. — Dissolve boracic acid {or borax previously moistened by 
drop of dilute sulphuric acid, to liberate boracic acid) in a little alcohol 
(C 2 H 5 H 0) and ignite. The flame has a peculiar green tint. This is a 
good test for the presence of a borate. 

Exp. 101. — Dissolve copper oxide in borax bead in oxidizing flame of 
the blowpipe. Color green when hot, Uue when cold. Change to reduc- 
ing flame, color, reddish-yellow. Dissolve Mn 2 , intense reddish-violet 
in oxidizing flame, in reducing flame almost colorless. (See Blowpvpf., 
Appendix.) 

Borax is largely used in blowpipe analysis as a "flux." 



Silicon is, next to O, the most abundant element, 
though, unlike O, it is always found combined (not free 
or native). The larger part of the earth's crust is silicon 



86 



CHEMICAL PRIMER. 




Fig-. 34 



uartz Crystal. 



oxide (Si 2 silica, white sand, quartz), 
or silicates. Many precious stones 
(amethyst, agate, etc.) are quartz col- 
ored with some metallic oxide. Sili- 
cates of K and Na, absorbed by roots, 
give by deposit of silica the stiffness 
and shining surface to corn-stocks and 
the edge of 'sword grass." Quartz 
veins often "carry" more or less free 
gold, and silver. 
Petrifaction is the replacement of wood by stone (sil- 
ica). Silica and certain silicates are soluble in water con- 
taining alkaline (K, Na, H 4 N) carbonates. As fast as 
the wood placed in the water decays, the silica is depos- 
ited, and copies very precisely the lines of the wood 
(knots, grain, etc.). 

Glass is a mixture of several silicates (as is also porce- 
lain). Crown or plate glass (common window glass) is 
chiefly calcium and sodium silicates. Ca hardens and 
gives luster. Na makes fusible, but gives greenish tint. 
Bohemian glass is chiefly calcium and potassium sili- 
cates. Potassium gives no color. 

Flint glass is chiefly K and Pb silicates. This can be 
ground into imitation gems, prisms, etc. When very rich 
in lead it is known as "paste." 

Exp. 102. — Into a piece of soft glass fuse cobalt oxide (CoO), the piece 
is colored a deep blue. 

Glass is colored any desired tint by fusing with a small quantity of 
some metallic oxide. "Purple of Cassius" (which see) is used for the 
finer ruby red; cuprous oxide also colors red; cupric, chromium, and 
ferrous oxides give green; cobalt oxide gives blue, arsenous oxide the 
white, soft enamel of lamp shades; manganese oxide violet, etc. 

Glass is annealed by being cooled very gradually for 
days. When cooled quickly, it is very brittle. Lamp 



BORON AND SILICON 87 



chimneys break from sudden change of temperature, 
because not properly annealed. 

Glass is etched by hydrofluoric acid as we have seen 
in Exp. 86. 

Pure clay (kaolin, china clay, H 2 AL 2 Si 2 8 + H 2 O) 
under the influence of heat forms a hard, porous solid. 
Pure feldspar (K 2 Na 2 Al 2 Si 6 16 ) when heated fuses to a 
colorless glass. If china clay and ground feldspar are 
heated together, the fused feldspar penetrates the porous, 
infusible clay, producing a hard, translucent, lustrous 
mass — porcelain. Besides the many well-known uses of 
porcelain, it is employed in the laboratory, as it resists 
the action of acids and is quite refractory. 

Stoneware differs from porcelain in opacity, due to the 
fact that the fused, feldspathic glass does not penetrate 
the entire porous mass of clay. 

In common earthenware a poorer clay is used. The glaz- 
ing is done by throwing common salt (Na CI) into the kiln 
when the burning is nearly complete. The salt volatilizes 
and chemical reactions produce sodium aluminum silicate, 
giving a glassy surface. 

Common pottery ware ("brown earthen") is made of 
the most impure forms of clay, usually colored reddish- 
brown with ferric and other oxides. It is often glazed 
with "lead" by mixing lead oxide or galena (Pb S) with 
the clay. 

Silicates (or silica) are most excellent substances to 
"make hills of," because of their insolubility and hard- 
ness. Evidently the earth's crust could not be made of sol- 
uble matter, nor could there be firm continents if the crust 
were made of soft material 



88 



CHEMICAL PRIMER. 



CHAPTER XXV. 



ARSENICUM, ANTIMONY, AND CHROMIUM. 



Arsenicum (sp. gr. 5.7) is a brittle, steel-gray solid 
(semi-metal), generally found in combination. Two sul- 
phides, yellow, As 2 S 3 (arsenous sulphide, orpiment) and 
red As 2 S 2 (realgar), occur native. This element is often 
called " Arsenic. 95 

Caution. — Care must be taken in experimenting with arsenicum, as 
itself and its compounds are violently poisonous. Use very small quan- 
tities in all experiments; especially avoid breathing H 3 As. (See Anti- 
dotes. ) 

Exp. 103. — Place in a small glass tube, closed at one end "white arse- 
nic" (As 2 3 arsenous oxide "ratsbane") of the bulk of a pin's head. 
Hold inclined and heat very gradually (more perfect crystals are formed 
than by rapid heating). The "arsenic" sublimes and condenses in 
minute, octahedral crystals in the upper and colder part of the tube. 
(Examine crystals with a lens. ) 

Exp. 104.— Perform Exp. 103 in a 
closed, drawn-out tube (Fig. 35), plac- 
ing above the arsenous oxide (anhy- 
dride) powdered charcoal, and first 
raising the charcoal to low red heat. 
A dark mirror-like ring of arsenicum 
condenses upon the tube above, and 
a garlic odor is distinctly perceived. 
Fi o* 35, [If heating is too rapid the carbon is 

thrown up by draft. Though not so sharply defined, the arsenicum 
mirror, in case of this accident, is readily distinguished from the char- 
coal.] 




AsA + 2 = 

arsenous from nitric 
oxide acid, an 
oxidizing 

agent 


As,0 5 

arsenic 
oxide 


AsA + 3H,0 = 

acid-forming water 
oxide 


: 2 H 3 As : 

acid 



ARSENICUM, ANTIMONY, AND CHROMIUM. 89 

•2 AsA + C 3 = 3C0 2 + As, 
Exp. 105. — Boil a few decigrams of "white arsenic" in water. 
AsA + 3H 2 = 2H 3 As0 3 

acid-forming water hydrogen 

oxide or arsenite 

anhydride (acid) 

Filter and preserve nitrate as a sample of an arsenite. (Of course 
this may be considered a solution of arsenous oxide in water. (See 
Exp. 11.) 

Exp. 106. — Place a little of As-A °f the bulk of a pin's head in ten 
drops of strong H N 3 , and, having raised to the boiling point, evapo- 
rate over water-bath nearly to dryness. Dilute with water, filter and 
preserve as an example of an arsenate, 
1. 



2. 



Exp. 107. — To copper sulphate solution (5 per cent.) add H 4 N H O 
till the precipitate formed is partially but not wholly dissolved. Filter, 
divide filtrate into two portions. To the first add drop by drop an 
arsemte, a green precipitate of acid copper arsenite (H Cu As 3 , 
"Scheele's Green," Paris green, etc., used as a pigment) falls. To the 
second portion add a few drops of an arsenate, an acid copper arsenate 
(H Cu As 0+) bluish.- g?*ee?2, falls. (See Acid-Salts.) 

Exp. 108. — To silver nitrate solution (2J per cent.) add H 4 N H till 
precipitate is partially but not wholly dissolved. Filter, divide filtrate 
into two portions and proceed as in Exp. 107; from first portion yellow 
silver arsenite (Ag 3 As0 3 ) falls; from the second portion a beautiful 
chocolate silver arsenate (Ag 3 As OJ falls. Add ammonium hydrate (or 
other moderately strong alkaline solution), each of the precipitates dis- 
solve. 

By the last experiment an arsenite may be readily dis- 
tinguished from an arsenate. The pupil may learn here 
that the chemist in analysis depends largely upon the 
color of precipitates and solubility (or insolubility) in 
various reagents. (See Exps. 109 and 111.) 

Arsenic acid is used in preparing aniline red (for dyeing), and other 
arsenates (especially Na 3 As OJ are used in calico printing. 



90 



CHEMICAL PRIMER. 



Exp. 109. — Into a small flask prepared with 
safety-funnel as in Fig. 36, and containing Zn, 
pour dilute H 2 S 4 and after air is expelled ignite 
as with philosopher's lamp. Pour through the fun- 
nel a few drops of arsenical solution (ate or ite). 
The color of the flame changes and the cold dish is 
smutted with arsenicum. (Just as a candle-flame 
smuts a cold dish with C. The arsenicum of the 
H 3 As is lowered below the igniting point, while 
the hydrogen is not. ) Upon the mirror-like spot 
place a drop of bleaching powder solution (or of hot 
strong nitric acid), it dissolves, unlike the antimo- 
nial spot. (See Exp. 111.) 

y 

Zn + EUSO, = ZnS0 4 + H 2 

s 




Fig. 36. 



(1) 



(2)-H s + As 

"nascent" 
hydrogen 



H 3 As 

inflammable 
gas 



(3)— 2H 3 As + 6 = 3H 2 + As,0 3 



from, 
air 



If a cold test-tube be placed over without touching the arsenical flame, 
octahedral and characteristic crystals of As 2 3 and moisture condense 
upon its sides. 

Note.— Don't breathe the gas H 3 As. The experiment should be per- 
formed under a gas chimney or near a window with outward draft. If 
a small test-tube (without safety-funnel) is taken instead of the flask, 
if but two or three drops of As 2 3 solution is used and the apparatus 
held at arm's length, the experiment is a perfectly safe one even in a 
closed room. This is stated so explicitly because a few teachers are 
overcautious and omit many experiments, while on the other hand a 
few are culpably careless. 

This last experiment is Marsh's test for "arsenic" (any 

compound of arsenicum). Of course in all tests the 
chemist must first make sure that his materials are pure, or 
at least free from the substance he is searching for in the 
unknown liquid or material. (See Magnesium.) 

Arsenicum (and its compounds) is a powerful antisep- 
tic. Bodies of those poisoned with it are sometimes pre- 



ARSENICUM, ANTIMONY, AND CHROMIUM. 91 

served from putrefaction for years. In small doses it 
stimulates and causes persons to grow fat. It is said to 
beautify the complexion, but its use is a very dangerous 
practice. All the symptoms of arsenical poisoning- 
appear, if one ceases the practice. It is a singular fact 
that in a certain district of Hungary the peasants habit- 
ually eat " arsenic " (As 2 3 ). 



Antimony (sp. gr. 6.7) is a brittle, highly crystalline 
solid (semi-metal), with brilliant luster. Upon the surface 
of its bluish-white masses are usually fern-like crystalli- 
zations. 

Exp. 110. — Into an acidulated (H CI) dilute solution of antimony 
(tirtar emetic, K Sb C 4 H 4 6 , potassium "antimony!" tartrate) pass 
H 2 S gas (or its solution). Sb 2 S 3 , antimonous sulphide, orange-yellow, 
falls. Filter, dry, and heat carefully; it turns grayish-black. 

Native antimonous Slllpllide (gray antimony, or antimony glance) 
is the source of the Sb of commerce. 

Exp. 111. — Perform Exp. 109, using antimonial solution instead of 
arsenical. Dark antimony spots are obtained. Upon one place solu- 
tion of bleaching powder, it is unaffected; upon another place a drop of 
hot nitric acid, it is oxidized (turned white, Sb 2 3 ), but not dissolved. 
(See Remarks, Exp. 108.) 

Antimony is a constituent of several important alloys, 
as type metal, etc. (See Alloys.) 

An alloy is a mechanical mixture of two or more 
metals (including semi-metals). If one of the metals is 
mercury, the alloy is called an amalgam. A mechanical 
mixture differs from a chemical compound in that it may 
contain its constituents in any proportions, but a chemi- 
cal compound must contain each constituent in some one 
proportion, or multiple of that proportion. 



92 CHEMICAL PRIMER. 

Chromium (sp. gr. 4.8) is a silver- white metal (considered a metal, 
though ordinarily negative to H). (Let the student learn right here 
that the order of elements in Table No. 1 is the usual order. Rarely an 
element takes a different position . when obtained by electrolysis under 
different circumstances, or from different compounds.) 

Chromium makes both acid-forming (Cr 3 ) and basic (Cr 2 3 ) oxides 
with corresponding acid (H 2 Cr 4 chromic acid) and base (Cr 2 6HO) 
respectively. 

The principal ore of chromium is " chromic iron ore" (Fe Cr 2 4 ). 
A few of its compounds are extensively used in the arts, viz. : potassium 
chromate (K 2 Cr0 4 ), potassium bichromate (di-) (K 2 Cr 2 7 ),and lead chro- 
mate (Pb Cr 4 ) "chrome yellow." (See Ana. Charts.) 



CHAPTER XXVI. 



GOLD AND PLATINUM. 

Note. — With this chapter we begin the study of the metals proper. 
In general, a metal is an elementary substance (1) with a peculiar 
luster, called metallic, (2) insoluble in water, (3) a good conductor of 
heat and electricity, (4) positive, with reference to hydrogen, and (5) 
uniting with H and to form bases. Chemists are not, however, 
agreed as to any precise definition, and the line between metals and 
non-metals cannot be sharply drawn. This is the case with terms used 
in all sciences (except in the exact sciences, included in the general term 
mathematics). No line can be drawn between soluble and insoluble 
substances, for one kind fades gradually into the other. For example, 
Pb is considered insoluble, but traces of the metal may be found in dis- 
tilled water that has been in a leaden dish for a day or two. It oxid- 
izes and dissolves. No line can be definitely drawn between "hot" 
substances and "cold" ones, but the terms are relative. The same is 
true of poisonous and non-poisonous substances. 

In the arts an alloy of two or more metals is often spoken of as "the 
metal," but this is a technical and loose use of the term. 



GOLD AND PLATINUM. 93 

For uses of the metals, reduction of their ores, etc., see fuller accounts 
in the cyclopaedia and in larger works on chemistry. See also Appendix. 

Gold (sp. gr. 19.3, fusing point 1,100°) is found native 
(free), frequently alloyed with silver, in quartz veins, allu- 
vial deposits ("placers"), etc. It is obtained by (1) 
quartz mining, (2) placer mining, and (3) hydraulic 
mining. 

Exp. 112. — Dissolve a piece of gold-leaf in globule of Hg. Place the 
amalgam on hard glass and in window with outward draft; keep at dull 
red heat for a little time. Hg distills leaving the gold. 

Mercury is used to extract gold from the sands or from 
pulverized quartz. The amalgam of Au and Hg is then 
submitted to pressure in "bags," which squeezes out much 
of the Hg. The remainder is driven off by distillation, 
but the Hg is saved, not thrown away as in the experi- 
ment. 

Gold is a very brilliant yellow solid, one of the most 
ductile and malleable of the metals (280,000 sheets of the 
finest gold-leaf make only one inch in thickness). It was 
known as the "king of metals," and together with plati- 
num and silver (also rare metals of platinum group) is 
called a noble metal. The others in contrast are called 
base metals. It is insoluble in any of the common acids, 
but dissolves in "aqua regia," chlorine- water, or bro- 
mine-water. 

Pure gold is too soft for jewelry, coin, etc., and is hardened by cop- 
per. A carat is -^. An alloy containing -||- pure gold is said to be 
gold of 16 carats fine. 

Aurous cyanide (Au C N) dissolved in solution of KCNis used in 
electro -gilding. The clean substance to be plated is. hung upon the neg- 
ative pole of the battery and gold upon the positive pole. 



04 CHEMICAL PRIMER. 

Platinum (sp. gr. 21.5, fas. pt. 2,000°) is found native, 
usually alloyed ("platinum ore") with iron, copper, or some 
of the rare metals (palladium used to color "salmon" 
bronze, rhodium, iridium used to tip gold pens, ruthe- 
nium and osmium) of the platinum group. Like gold, 
it is insoluble in any one of the common acids, but dis- 
solves in chlorine-water, and slowly in aqua regia 
(H CI + H N 3 ). Its "ore" is worked by means of the 
oxy-hydrogen blowpipe, coal gas being usually used in 
place of H. It is a very ductile metal. 

Platinum — because of its high fusing" point and its insolubility in 
most liquids — is to the chemist an exceedingly useful metal. From it 
he makes crucibles, stills (see H 2 S 4 ), wire, blowpipe tips, etc. 



CHAPTER XXVII, 



SILVER, MERCURY, AND LEAD. 

Silver (sp. gr. 10.5, fun. pt. 1,040°) is found native, often 
alloyed with copper, mercury, and gold. Ag 2 S (mixed 
with other sulphides, as galena, Pb S) and Ag CI ("horn 
silver") are among its chief ores. 

Exp. 113. — Repeat Exp. 6 and place the resulting Ag CI, mixed with 
a little K 2 G 3 (or Na 2 C 3 ) upon charcoal and heat in reducing flame 
of the blowpipe. A silver globule ("button") is obtained. 

(1)-K 2 C0 3 + 2AgCl = Ag 2 C0 3 + 2KC1 
(2)~Ag 2 C0 3 = Ag 2 + C0 2 

s 

(3)-2Ag 2 + C = Ag, + C0 2 

deoxidizing 
agent 



SILVER, MERCURY, AND LEAD. 95 



The melted globule absorbs oxygen from the air, and if cooled quickly 
the escaping breaks the hardening surface, and the melted ("molten") 
silver runs out ("spitting" or "sprouting"). 

Silver is a brilliant white metal. For jewelry, coin, 
etc., it is hardened with Cu. It is used for silvering mir- 
rors because it takes a high polish. It is not acted upon 
by fused caustic alkalies (K H O, Na H O, etc.), as glass 
and platinum are, and hence certain chemical vessels are 
made from the metal. It expands at the moment of solid- 
ification and hence can be cast (copies fine lines of the 
mould). 

Silver is obtained from the sulphide by (1) roasting the pulverized 
ore with salt, Ag 2 S + 2 Na CI = 2 Ag CI + Na 2 S, and (2) by placing 
the Ag CI in a cylinder with H 2 0, Hg and Fe scraps, 2 Ag CI + Fe == 
Fe Cl 2 + Ag 2 . The Hg forms an amalgam with silver from which the 
Ag is obtained, as gold is obtained from gold amalgam. The process 
of Exp. 113 is too expensive for the practical miner, though used by the 
assayer. 

Silver may be freed from lead by fusing the alloy, and as Pb crys- 
tallizes first it may be skimmed out. This leaves a portion of the Pb, 
which may be completely extracted by cupellation. (A cupel is a 
shallow dish made of bone ashes. ) The Ag containing Pb and other 
impurities is placed in the cupel and raised to the red heat. A hot cur- 
rent of air plays upon the fused mass. The Pb is oxidized and the Pb O 
is absorbed by the cupel. After a while the refiner sees the mirror-like 
globule of pure silver and quickly removes it, lest it also oxidize and 
waste. 

Silver nitrate (Ag N 3 , lunar caustic) is the most important salt 
of silver. It forms with organic compounds by the action of light a 
very stable, dark compound, and hence is used in indelible inks. 
Hair dyes sometimes contain it, but these are highly injurious. 

The changes which the salts of silver undergo when exposed to light, 
especially in presence of organic matter, is the basis of photogra- 
phy. (See Exp. 6, Note.) 

Exp. 114. — Borrow an old "negative" from a photographer, and upon 
a sheet of prepared paper (moistened with silver salt and dried in the 



96 CHEMICAL PRIMER. 

dark) furnished by him, print by means of a few moments' exposure 
to direct sunlight, a photograph. After removal and a few hours' 
exposure (even to reflected light), the picture fades out, because the 
entire paper turns black. Strictly the picture does not "fade out," 
but the background " comes in." 

The photographer applies reagents to dissolve from the unblackened 
portion the silver salt, and thus preserves the picture. In preparing 
the negative he first covers the glass with an organic film (collodion) to 
receive the silver salts. (Hold a lens up between the window and a 
sheet of paper. The lens converges the rays of light and forms an in- 
verted image of the window upon the paper. This explains the forma- 
tion of the " negative " in the dark " camera.") After the formation 
of the image, he treats the slide (glass) with reagents, whose action 
upon the part previously influenced by the light is different from their 
action upon the part uninfluenced by the light. But the simple prin- 
ciple of photography should be learned here, not the art. (See 
Appendix.) 

A solution of Ag C N in solution of KCNis used in electroplating. 
The clean substance to be plated is hung upon the negative pole, and 
silver upon the positive. 



Mercury or "quicksilver" (sp. gr. 13.5, fus. pt., i. e., 
freezing point — 39.4°) is found native in small quantities, 
but its chief source is the ore cinnabar (Hg S mercuric 
sulphide) from which the liquid metal is obtained by mix- 
ing with iron turnings (or lime) and distilling. 
HgS + Fe = FeS + Hg 

When Hg S is prepared artificially (by "subliming" together S and 
Hg) it is called vermilion and is used as a pigment. 

Mercury is largely used in making thermometers, ba- 
rometers, etc., for collecting gases soluble in water (see 
Fig. 24), for extracting go^ and silver from their ores, 
for silvering mirrors (tin amalgam), and formerly was 
much more used in medicine than now. 



SILVER, MERCURY, AND LEAD. 97 

"Blue pill" is Hg "rubbed up" with confection of roses 
till the globules are not visible to the naked eye. Blue 
ointment is mercury "rubbed up" with lard. 

Exp. 115. — Pour a little dilute nitric acid upon a considerable quan- 
tity of Hg, and, bringing to boiling point, leave over night; pour off 
from the excess of Hg and preserve as solution of mercuroi^s nitrate 
(Hg 2 2 N" 3 ). Dissolve a small globule of Hg completely in an excess of 
hot, strong nitric acid. Evaporate nearly to dryness, dilute and pre- 
serve as solution of mercuric nitrate (Hg 2 N 3 ). (Of course these salts 
may be obtained dry by evaporation over a water- bath. ) 

Exp. 116. — To a solution of mercurous nitrate add H CI. 

Hg 2 2N0 3 + 2HC1 = Hg 2 Cl 2 + 2HN0 3 

white 
precipitate 

Mercurous chloride (calomel, Hg 2 Cl 2 ) is an insoluble 
(in water) white powder. It acts powerfully upon the 
glandular system (liver, etc.), and in large or long contin- 
ued doses produces salivation (excessive action of the sal- 
ivary glands) and other serious results. It was formerly 
used in medicine much more than now, by some almost 
as a "cure all." 

Exp. 117. — To a solution of mercuric nitrate add H CI. 

Hg2N0 3 + 2 H CI = Hg Cl 2 + 2 H 1ST 3 

There is no precipitate because Hg Cl 2 is soluble. Place one drop of 
the solution on clean glass and evaporate at low heat. White crystals 
of Hg Cl 2 are obtained. 

Mercuric chloride (Hg Cl 2 corrosive sublimate) is a 

powerful poison and a strong antiseptic. It is used to 
prevent the decay of wood, and its dilute solution in alco- 
hol brushed over specimens in Natural History preserves 
them. (See Antidotes.) 



98 CHEMICAL PRIMER. 



Lead (sp. gr. 11.4, fus. pt. 334°) is rarely found free. 
Its chief ore is lead sulphide (Pb S, galena), often carrying 
Ag 2 S. The roasting ("smelting") of this ore and separa- 
tion of the metal is a very simple process. Pb is soft and 
malleable, and when fresh cut has a lustrous bluish-gray 
color, quickly dulled by oxidation. Its common uses are 
well known to every school-boy. It contracts in solidify- 
ing, and hence will not make accurate castings (i. e., will 
not copy the fine lines of the mould). 

Exp. 118. — Make two moulds by boring conical cavities into plaster 
of Paris (Ca S 4 , 2 H 2 0) and making fine, clean-cut grooves on the 
sides. Into one pour pure melted lead. Into the other pour melted 
lead, in which a little Sb and Sn has been previously dissolved (type 
metal). The first casting is blunt and does not copy the grooves; the 
second is sharp, pointed, and copies the grooves accurately. This is 
caused by expansion of the crystalline Sb and Sn in solidifying. [Sb 
alone may be used as well.] 

Water used for drinking purposes should not be brought 
great distances in lead pipes (unless the water contains 
considerable quantities of phosphates, carbonates, or sul- 
phates, which coat the lead with white coat), and water 
that has stood over night in the short lead pipe connect- 
ing with faucet should be allowed to run out before drink- 
ing. Water containing even minute quantities (and 
otherwise practically harmless) of ammoniacal salts (from 
decomposition of organic matter) dissolves lead and keeps 
the surface bright. Chronic lead poisoning is produced 
by drinking such water. Lead is an "accumulative" 
poison, i.e., it remains in the system and is thrown off 
with difficulty. Painters are often attacked by "colic" 
produced by lead poisoning. 

Fruit cans should not be soldered with an alloy of Pb. (See Exp. 120 
and connection.) Metallic Pb is not poisonous because of its insolubil- 
ity. (Plumbers are not attacked by "lead colic") 



SILVER, MERCURY, AND LEAD. 



99 




Litharge (Pb 0) (see Exp. 50)— "reel lead" (Pb 3 4 )— "sHgrar of 
lead M I lead acetate Pb 2 C, H 3 2 ). and " white lead " chiefly (Pb C 3 
but containing a little Pb 2 H 0) used in painting, are important com- 
pounds. All are poisonous, especially the 
very soluble acetate. (.see Antidotes, also 
Exp. 12.) 

White lead is made as represented in 
Fig. 37. A roll of lead (B) is placed in an 
earthen vessel, and below, weak vinegar (A). 
Above (and around i is packed decaying tan- 
bark (C) and refuse. These vessels are 
arranged in immense piles; the heat of the 
decomposition assists the evaporation of the 
vinegar, and in rive or six weeks the lead is 
all converted into Pb C 0^. 



Fig'. 37. 



Pb 



H C 2 H 3 2 



Pb H C,H 3 2 

basic salt 



CO, + 

from decomposing 



Pb H C 2 H 3 2 

basic lead 

acetate 
(see basic salts) 



= PbC0 3 + HCELO, 



"white 
lead" 



unites with 

another portioi 

of Pb 



White lead is often largely adulterated with gypsum (Ca S 0^ 2 H 2 0) 
heavy spar (Ba S OJ, etc. Pure Pb C 3 dissolves completely in hot 
dilute H X 3 , and the adulteration is easily detected. 

Exp. 119. — Add a little mucilage to lead acetate solution (sympathetic 
ink) and write with fine hand a few words. Dry; they are invisible. 
Moisten the paper and allow H 2 S gas to come in contact with it. The 
letters become black. (See Exp. 9.) 

H 2 S is a test for lead, and, vice versa, lead acetate (paper moistened with 
it) is a test for H 2 S. "A body acted upon characteristically by a reagent is 
as i/ood a test for the reagent as the reagent is for it," — Attfield. (See test 
in Ax a. Charts.) 



100 CHEMICAL PRIMER. 



CHAPTER XXVIII. 



Cu, Fe, Zn, and Sn. 

Copper (sp. gr. 8.9, fus. pt. 1,200°) is found free in large 
masses (Lake Superior mines). Its most common ore is 
copper pyritas (Fe Cu S,), from which it is obtained by 
roasting with a silicate, or with silica (Si O,), to remove 
the iron as iron silicate, and again roasting the Cu S. It 
is a reddish metal, highly malleable and ductile. With 
the exception of Ag it is the best conductor of heat and 
electricity. Brass, bronze, and bell-metal contain Cu. 
(See Alloys.) 

The salts of copper are poisonous. (See Antidotes.) 
Substances containing acids (fruits, jellies, pickles, etc.) 
should never be put in copper (or brass) utensils. Fats 
dissolve copper oxide, and therefore should be put into 
copper dishes only when the vessels are bright. Copper 
sulphate ("blue vitriol," "blue stone" Cu S 4 5 H 2 0) is 
used in calico printing and in galvanic batteries. (See 
Exp. 34.) The native malachite (Cu C 3 + Cu 2 H O) 
takes a high polish and is used for jewelry and other 
ornamental articles. Verdigris is copper acetate 
(Cu 2 C 2 H 3 0. 2 ) though the name is often applied to the 
artificial carbonate. 



C?/ y Fe, Zn, and Sn. 101 

Iron (sp. gr. 7.8, fus. pt. 1,000° to 1,800°) is the most 
important of all the metals. It is rarely found free 
(always found free in aerolites) but in combination it is 
widely distributed, traces being found in the blood of ani- 
mals and in the juices of plants. It is a soft, silver-white 
metal (if pure). Among the most important of its 
numerous ores are Fe 2 3 ("specular iron" hematite) — 
Fe 2 6 H O + Fe 2 3 (brown hematite, limonite) — Fe 3 4 
("magnetic iron"), and Fe C 3 (spathic iron, ferrous car- 
bonate). The value of the ore depends as much upon the 
nature of its impurities as upon the percentage of iron. 

The old process of reduction ("Direct Process") was to roast the ore 
with charcoal in an open "forge" fire. The pasty mass of reduced iron, 
called "bloom" separates from the fused silicates (or fused glass), called 
"slag." 

The modern process ("Indirect") consists of two parts, (1) obtaining 
the reduced iron from the ore, not pure, but containing a large percent- 
age of C. (This is cast iron, or "pig iron.' 5 ) (2) The production of 
iron nearly free from C ("wrought iron") from the cast iron. 

1. The ore is placed in a "blast furnace" with layers of coal, coke, 
and "flux" [the last, limestone Ca C 3 , if impurities are silicates 
(clayey), and silicates, if the impurities are calcareous. Of course, the 
object is to form a "slag" of calcium glass]. Hot air is driven in below. 
The heat of the furnace is intense and its action continuous. The "life" 
of the furnace fire is often twenty years, fresh material being ceaselessly 
supplied from above. The melted iron and "slag" (floating on iron) is 
drawn off below. [The hot C 2 and unburnt gases passing from 
chimney are utilized for heating the air driven in below.] The iron 
runs into a large main, called "sow," and thence into lateral moulds 
called "pigs" (hence "pig iron"). 

2. Pig iron (2 to 5 per cent, of C) is changed to wrought iron (less 
than J per cent, of C) by burning out the C (also S, Si, and P) in a 
reverberatory furnace, "puddling furnace" (Fig. 38). Fuel burns upon 
the grate A; pig iron is placed upon the floor B, and is frequently stirred 
by means of openings in the side. 



102 



CHEMICAL PRIMER. 




Fig-; 38. 

Steel contains more C than wrought iron and less than 
cast iron. It may be made by heating bars of wrought 
iron to redness in contact with powdered charcoal for eight 
or ten days. This is called the cementation process. 

Bessemer steel is made by decarbonizing the best pig 
iron (free from phosphorus and sulphur) at a fearful heat 
in an egg-shaped vessel Q c converter") lined with infusible 
material. Hot air is driven in below through numerous 
openings by means of a powerful engine. Si is also re- 
moved. "Looking-glass" iron containing a known quan- 
tity of C and a little Mn is then added. Bessemer 's proc- 
ess is a rapid one. Bessemer steel is largely used in 
constructing railroads, bridges, etc. 

Steel expands at the moment of solidification and there- 
fore can be cast. Few metals besides iron can be welded. 
(To be welded a metal must soften before melting.) 
Cast iron cannot be welded. Iron (or its salts) is largely 
used in medicine as a tonic. 

FeiTOUS sulphate (Fe S 4 , 7 H 2 0, green vitriol, copperas) is used 
in dyeing, making ink, etc. Fe S is used in preparing the reagent H 2 S 
(Exp. 8). Iron disulphide (Fe S 2 , iron pyrites, "fool's gold") may be 
readily distinguished from gold by heating and observing the odor of 
S 2 and also the change in color. (See Exp. 91.) 



Cm, Fe, Zn, and Sn. 103 

Zinc (sp. gr. 6.9, fus. pt. 410°) very rarely occurs native. 
Its chief ores are Zn C 3 (smithsonite), Zn S (zinc 
blende), and Zn O ("red zinc ore" colored red by an oxide 
of Mn). It is a bluish-white crystalline metal. Fe dipped 
in melted Zn is coated with the metal and forms what is 
termed galvanized iron. Water that has stood a long 
time in zinc-lined vessels (tanks) is unfit to drink. Zn O 
(zinc white) is used as paint. (See Alloys.) 



Tin (sp. gr. 7.3, fus. pt. 230°) is obtained from its prin- 
cipal ore Sn 2 (tin dioxide, stannic oxide, "tin stone") 
by roasting with carbon in reverberatory furnace. It is 
a lustrous, white, highly crystalline metal, malleable and 
ductile. When a bar of tin is bent, a crackling sound 
("tin cry"), caused by the friction among the crystals, is 
heard. 

"Tinware 55 is really iron ware coated with Sn (by 
dipping the iron into melted tin). When the tin wears off, 
the iron rust (Fe 2 3 , or hydrated Fe 2 6 H O) is seen. Tin 
is often adulterated with (the cheaper) lead. Fruit con- 
tained in cans coated with such "tin" is unfit to eat, for 
it contains poisonous lead salts. Solder for such cans 
should contain no lead. Pb is easily detected by 

Exp. 120. — Upon a piece of "tin" (tinned iron) place a drop of 
HN0 3 and evaporate to dryness. Add a drop of K I solution, yellow 
Pb I 2 is formed if lead is present. [Try the experiment with a piece 
of "tin" upon which a minute piece of lead has been melted, forming 
alloy.] 

P1)2N0 3 + 2KI — 2KN0 3 + Pbl 2 

yellow 

Pins made of brass wire, copper utensils, iron tacks, etc., are often 
covered with a thin coat of tin to give bright surface. Tin is largely 
used in making alloys (which see). 

Tin disulphide (Sn S 2 ), a bright golden-yellow, is known as mosaic 
gold, and is used in decorative painting. Sn Cl a (stannous chloride) 
and Sn Cl^ (ic) are largely used in dyeing. 



104 CHEMICAL PRIMER. 



CHAPTER XXIX. 



Bi, Co, Ni, Mn, Al, and Mg. 

Bismuth (sp. gr. 9.8, fus. pt. 264°) is a brittle, purplish- 
white, crystalline metal. It forms alloys with other met- 
als, expanding much in solidifying and remarkable for 
their low melting point. 

Exp. 121.— Fuse Bi (5 dcg.), Pb (3 dcg.), and Sn (2 dcg.) together. 
The alloy is fusible metal (one variety). Place the cold globule in 
water and raise to the boiling point. Notice that the alloy melts (at 
91.6°) before the water boils. 

Fusible metal is used for taking casts of wood cuts, etc. Fusible 
metal (of different composition and melting at some definite point above 
100°) is used for "safety plugs" in steam boilers. When the tempera- 
ture approaches a point that would be dangerous, the plugs melt and 
let the steam escape. 



Cobalt (sp. gr. 8.6) is a silver-white metal. Its salts (acetate, sul- 
phate, nitrate, chloride) are used for sympathetic ink. (See cyclopaedia.) 

Exp. 122. — Thicken a solution of cobalt chloride with a little pure 
mucilage. Write with a fine pen upon paper. The writing is invisible. 
Heat upon metallic support. The writing is distinctly blue. [Dry 
Co Cl 2 is distinctly blue, but moist Co CL, has a pale pink color and is 
invisible when thin spread. The salt is deliquescent.] The ink becomes 
invisible again when the paper cools. 



Nickel (sp. gr. 8.9) is a lustrous white metal, taking a 
high polish. It is used for plating iron to protect from 
rusting. It is largely used in alloys, 



Bi\ Co, JVt] Mn, Al, and Mg. 105 



Exp. 123. — Repeat Exp. 122, using cobalt solution, to which nickel 
chloride has been added. The writing is green. [Nickel salts are used 
to make green sympathetic ink.] 



- Manganese (sp. gr. 8, fus. pt. about 1,800°) is a hard, 
brittle metal. It easily oxidizes in the air and hence is 
not found free. It is best kept under petroleum. 

Manganese dioxide (Mn 2 , see preparation of and CI) is its most 
important ore. Manganates (dyad grouping Mn 4 ) and permanga- 
nates (dyad grouping Mn 2 & ) are largely used as disinfectants. 

Exp. 124. — Place a small piece of fresh meat in a test-tube of water 
and leave till putrefaction begins. Filter (through paper) and let fall 
into it a single drop of dilute potassium permanganate (K 2 Mn 2 8 ). 
Place beside it a second test-tube of distilled water in which the same 
amount of permanganate has been put. Leave both over night. The 
permanganate in the first test-tube is decolorized, having given up a 
part of its to the decomposed organic matter. In the second the 
color remains. [The presence of ferrous salts, or other easily oxidizable 
substances, must be avoided. Water through which the breath has 
been blown by means of a glass tube answers for the test.] 

Potassium permanganate is a powerful oxidizing 
agent and is a very delicate test for the presence of 
decomposing organic matter. [In such tests be careful 
not to add too much K 2 Mn 2 8 , as of course the excess 
would not be decolorized.] 



Aluminum (or aluminium, sp. gr. 2.6, fus. pt. 700°) is a 
bluish-white metal, taking a bright polish. Next to sili- 
con and oxygen it is the most abundant element in the 
earth's crust. It does not readily oxidize in the air. 
Delicate, light weights, and, in general, instruments need- 
ing lightness and moderate strength are made from alum- 
inum. 



106 CHEMICAL PRIMER. 

Aluminum lias been recently obtained directly from co- 
rundum by heating the oxide with charcoal in a closed fur- 
nace by strong electric current. So many are the uses to 
which Al could be put, so abundant is the combined element 
in the earth's crust, and so certain is it that a cheap process 
of extracting it will sometime be found, — that our more 
enthusiastic chemists have called it " the coming metal." 

Aluminum bronze (Cu 90 per cent., Al 10 per cent.) is a very hard 
alloy, malleable, has the color of gold, and takes a fine polish. 

Aluminum oxide (A1 2 3 ) occurs in corundum, ruby, sapphire, and 
emery (impure). 

Common clay is chiefly aluminum silicate, Al 2 Si 2 7 (there are 
numerous silicate "groupings"), but no cheap method of obtaining the 
metal has yet been discovered. Al would be extensively used were it 
not for its high price. (See Glass and Porcelain.) 

Common alum is a double sulphate (Al 2 K 2 4 S 4 , 24 H 2 0) contain- 
ing much water of crystallization. Ammonium alum [Al 2 (H 4 N) 2 4 S 4 , 
24 H 2 0] is also somewhat common. Alum is much used as a "mor- 
dant" in dyeing. (See Dyeing.) Cryolite is Al 2 F 6 + 6 Na F. 



Magnesium (sp. gr. 1.75, fus. pt. about 2,000°, but ignit- 
ing point is low, the flame of a candle being sufficient to 
set it on fire) is a silver-white metal not found native, but 
in combination is widely distributed. 

The light from burning Mg is rich in chemical (actinic) 
rays, and hence is used for photographing in dark caves, 
etc. Arsenicum is never found with it, and the metal is 
used instead of Zn in important tests for As. (See 
Marsh's test.) 

Mg Cl 2 is found in sea water. Mg S 4 , 7 H 2 O (Epsom salt) is found 
in many mineral waters and in sea water. "Magnesia alba" is an arti- 
ficial mixture of Mg C 3 and Mg 2 H O, principally the former. (See 
magnesite, hornblende, meerschaum, soapstone, talc, serpentine, dolo- 
mite, etc., in cyclopaedia. ) 



CALCIUM. STROXTIUM, AXD BARIUM. 107 



CHAPTER XXX. 



CALCIUM, STRONTIUM, AND BARIUM. 

Calcium (sp. gr. 1.58) is a light-yellow, ductile metal. 
It oxidizes in moist air and consequently is not found 
native (free). Its compounds are widely diffused. 

Calcium oxide (Ca O, quicklime, a basic oxide, Exp. 5) 
is prepared by heating the native carbonate (Ca C 3 ) in 
egg-shaped "kilns" till C O, is all expelled. A kiln in 
which the process is continuous is shown in Fig. 39. 

S 

Reaction: Ca C 3 = Ca O + C O a 

Mixed with sand, hair, etc., according to the purpose 
for which it is intended, calcium oxide is used for making 
mortar, cements, etc. 

The principal reactions are: — 

(1)— Ca O + H 2 O = Ca 2 H O 

''water-slacked 
lime" 

When exposed to the air. this absorbs C 2 and hardens. 
(2)— Ca 2 H O + G O, = Ca G O s + H,0 

"water-slacked from "air-slacked evaporates 

lime" air lime*' 



108 



CHEMICAL PRIMER. 



Hydraulic mortars possess the 
power of hardening under water. 
These are made from quicklime 
that has been prepared from cal- 
cium carbonate containing a large 
percentage of silicates. Roman 
cement is made from calcium oxide 
containing from 25 to 35 per cent, 
of clay and hardens under water 
in a few hours. Chalk and clay 
thoroughly ground together with 
water, dried, and carefully burnt 
in kilns, produce an impure quick- 
lime from which a good hydraulic 
mortar, called Portland cement, is 
made. The hardening of these 
mortars, like those above, depends 
upon the formation of calcium 
carbonate. 




Fig. 39. A — fire. C— ash-pit. Calcium car- 
bonate is put in at top of furnace and 
calcium oxide removed at B. 

It 



Ca falls to a povvder when gradually air-slacked by exposure, 
first absorbs water and then C 2 as in above reactions. 

Ca is used in the laboratory for drying gases (Exps. 45, 56, and 
illuminating gas) and in the "lime light" (see Appendix), the flame of 
the oxy-hydrogen blowpipe raising it to the white heat and causing it to 
emit an intense light. 

Calcium carbonate (Ca C O s ) is found as marble, lime- 
stone, shells (chalk is formed by beds of tiny shells), sta- 
lactites, etc., also with Ca 3 2 P 4 in bones. (See Hard 
Water and Exp. 51.) 

Calcium sulphate (Ca S 4 , anhydrite) and calcium sul- 
phate with water of crystallization (Ca S 4 , 2 H 2 O 
gypsum, plaster, alabaster) occur native. When heated 
to 120°, gypsum parts with its water of crystallization, 
forming "plaster of Paris. 59 This plaster soon hardens 
("sets") when mixed with water and hence is used as 
cement, and for taking casts. (See Water permanently 
hard.) 



CALCIUM, STRONTIUM, AND BARIUM. 109 

Calcium chloride (Ca CL) has so strong an attraction for water that it 
is deliquescent. It is used for drying gases and is a constituent of 
bleaching powder (which see). 

Calcium fluoride (Ca F 2 , fluor spar) occurs native and is used as a flux 
in the reduction of metals. The peculiar glowing of this mineral when 
heated gave rise to the term fluorescence. Hydrofluoric acid is prepared 
from this salt by the action of sulphuric acid. (See Exp. 86.) 



Barium (sp. gr. 4) and Strontium (sp. gr. 2.5) 

ble calcium. 



reselli- 




ng. 40. 



Exp. 125. — Dissolve a barium 
salt in a little dilute H CI. Make 
a loop upon one end of a short plat- 
inum wire and fuse upon the other 
end a piece of glass tubing for a 
handle. Introduce into the lower 
and outer flame of Bunsen's burner 
(Fig. 40) by means of this loop a 
little of Ba salt solution. The 
flame is colored green. [Ba Cl 2 dis- 
solved in water answers.] 



Barium salts (especially Ba 2 N 3 ) are used to give 
the color in green fire (in pyrotechny) and this color is a 
very good test for soluble or volatilizable salts of Ba. 

Barium sulphate (Ba S 4 , heavy spar) is often used to adulterate 
white lead (Pb C 3 ). Barium chloride (Ba Cl 2 ) is test for soluble sul- 
phates. (Exp. 94.) 

Exp. 126. — Repeat Exp. 125, using Sr salt instead of Ba salt. The 
flame is colored red. Perform together on opposite sides of flame. 

Strontium salts are used to give the color in red fire, 
and this color is a very good test for soluble or volatiliza- 
ble salts of Sr. 



110 



CHEMICAL PRIMER. 



CHAPTER XXXI, 



POTASSIUM, SODIUM, AMMONIUM. 

Potassium (sp. gr. .87, f us. pt. 63°) is a light, bluish- 
white metal, soft enough (at 15°) to be spread with a 
knife. 

Exp. 127. — Cut a small slice of K upon 
blotting paper. Trim away the edges and 
throw the cleaned piece upon water in a 
beaker. Cover with glass plate (impurities 
cause spattering). The K decomposes the 
water. 

> 
K + H 2 = K H + H 

The reaction is so violent that the liber- 
ated hydrogen takes fire, and in burning 
the heat volatilizes a little of the K, which 




Fig. 41. 



in burning colors the flame purple. 

The affinity of potassium for is so great that it must 
be kept under naphtha (C 10 H 16 containing no O). Exp. 127 
proves that it cannot be found free or native. 

The compounds of K are widely distributed. They are constituents 
of all plants and of the bodies of animals. Potassium hydrate (KHO 
" caustic potash") is a white solid made from K 2 C 3 by action of 
Ca 2 H (and heat). 

K 2 C0 3 + Ca2HO = 2 KHO + CaC0 3 

It is largely used in the manufacture of soap. It is one of the strong- 
est alkalies known. (See Soap and Antidotes.) 



POTASSIUM, SODIUM, AMMONIUM. Ill 

Potassium carbonate (K 2 C 3 "pearlash") is prepared 
by leaching wood ashes, evaporating the "lye" in large 
pots (hence potash), and purifying by crystallization. It 
is a deliquescent salt, with a strong alkaline reaction. It 
(or Na 2 C 3 ) is largely used in chemical analysis. [See 
Axa. Charts, silver, lead, etc.] It reacts with insohible 
silicates by change of partners. 

The metallic L the metallic 

. v , potassium potassium , , 

silicate +i. , = -t x + carbonate 

,. i t i n carbonate silicate / -i i i \ 

• (insoluble) (soluble) 

"Saleratus" (H K C 3 bicarbonate of potash, acid salt with 
alkaline reaction, see Acid-Salts) may be prepared by passing C 2 
through strong solution of the normal salt (K 2 C 3 ). 

H,0 + C0 2 = H 2 C0 3 
K 2 C0 3 + H 2 C0 3 = 2HKC0 3 

Potassium nitrate (K N 3 saltpetre, nitre) together 
with Ca 2N0 3 and Na N 3 , is formed by the decom- 
position of refuse organic matter. The white incrustation 
often seen about such matter is principally K N 3 . It 
is a strong antiseptic, and is used with Na CI (common 
^alt) for preserving meat. It is largely used in the man- 
ufacture of gunpowder. When gunpowder burns, the 
reaction may be represented thus: — 

+ 3 G 2 



2KN0 3 


+ s + C 3 = 


K. 2 S + 


N a 


solid 


solid solid 


gas at 


gas 


oxidizing 


combustible combustible 


temperature 




agejt 


substance substance 


of explosion 





Fireworks are composed of gunpowder containing an 
excess of C and S with coloring matter. 

Potassium chlorate (K CI 3 ) is largely used for making oxygen 
and as an oxidizing agent. (Exp. 19, 79, 98, and Matches.) It is 
much used in medicine to allay inflammation of the throat (as gargle), 
etc. K 2 Cr 2 7 forms chrome yellow with lead salts. (Axa. Charts.) 
— The intensely poisonous K C N" (solution) dissolves gold and silver 
cyanides for electroplating. 



112 



CHEMICAL PRIMER. 



K CI resembles Na CI. Potassium salts are largely used in medicine. 

Exp. 128. — Repeat Exp. 125, using potassium salt instead of barium 
salt. The flame is colored purplish. Perform Exp. 130 on opposite side. 

This is a fair test for potassium compounds. Careful flame tests are 
of great value to the experienced chemist. (See Spectroscope.) 



Sodium (sp. gr. .97) is a light, silver-white, soft metal, 
resembling potassium. It is used as a reducing agent in 

preparing silicon, bo- 
and 



ron, magnesium, 
aluminum. 

Exp. 129. — Place a small 

clean piece of Na on water 
and quickly press below 
mouth of inverted test-tube 
by means of wire gauze at- 
tached to wooden rod. The 
water is decomposed and 
the H, set free, collects in 
test-tube. (If Na is thrown 
on hot water the liberated 
H immediately takes fire.) 

= NaHO + H 




Fig. 42.— Decomposing Water by Sodium. 



Na + H 2 

The above experiment proves that sodium cannot be 
found free. Like potassium, it must be kept under 
naphtha. 

Exp. 130. — Repeat Exp. 125, using sodium salt instead of barium 
salt. The flame is colored yellow. 

Sodium chloride (Na CI, common salt) is the most 
abundant of the sodium compounds. It is the source from 
which most compounds and sodium itself are obtained. 
Its distribution in larger or smaller quantities is almost 
universal, traces which the spectroscope reveals being 
found in the atmosphere. It is obtained from immense 



POTASSIUM, SODIUM, AMMONIUM. 113 

deposits or beds, from saline springs and sea-water (by 
evaporation). It crystallizes in cubes. (See Crystal- 
lization.) It is one of our most common antiseptics. 

Sodium sulphate (Na 2 S A 10 H 2 0, Glauber's salts) is remarkably 
efflorescent. 

Sodium carbonate (Na 2 C 3 10 H 2 O, sal soda) is ex- 
tensively used in the arts. It is made by Leblanc's 
process :— 

(1) Common salt and sulphuric acid are heated. 
2NaCl + H 2 SO, = Na,S 4 + 2 H CI 

The hydrochloric acid is saved by being absorbed (see 
Exp. 75, and comments) in tower of coke wet with con- 
stantly falling water. 

(2) The Na 2 S O, is heated with Ca C 3 (equal wt.) 
and C (half its wt.) in a reverberatory furnace. 

(a)— Na 2 S 4 + C 2 = Na 2 S + 2 C 2 

reducing 
agent 

(b)— Na 2 S + Ca CO s ^ Na 2 C 3 + Ca S 

insoluble 

\ . — -— y - I 

"black ash" 

The ]STa 2 C 3 is then washed out (lixiviated) from the 
" black ash " and purified by crystallization. Cheap sodium 
carbonate gives us cheap glass, cheap soap, and an inex- 
pensive method of softening hard water. 

Acid sodium Carbonate (H N& C 3 , bicarbonate of soda, "soda" 
of cook-room, see Acid-Salts) has alkaline reaction, and is prepared by 
passing C : into the normal salt (see HKC 3 ). 

Sodium hydrate (Na H 0, caustic soda) is made from sodium car- 
bonate (just asKHO from K 2 C ? .) and is used in the manufacture of 
hard soap. 

Sodium nitrate (ETa N 3 , Chilian saltpeter) is a deliquescent salt. 
8 



114 CHEMICAL PRIMER. 

Ammonium (H*N, a hypothetical metal), as we have 
seen, is a compound radical, closely allied to K and Na. 
Though it has never been isolated, an alloy of ammonium 
and mercury (i. e., an amalgam) has been formed. 

Ammonium chloride (H 4 N CI, sal ammoniac) is used in medicine, in 
dyeing, in soldering, and in the laboratory as a reagent and source of 
ammonia (H 3 N, see Exp. 45). A solution of this salt forms the fluid 
used in the Leclanche (bell- ringing) battery. 

Ammonium nitrate (Exp. 36) and ammonium carbonate (see Anti- 
dotes) are important salts. 

Microcosmic salt (H Na H 4 N P 4 + 4 H 2 0, see Double Salts) is 
largely used in blowpipe analysis as a flux. 

Ammonium hydrate (H 4 XHO "ammonia water") is a 
very strong base, and is extensively used (dilute) as a 
cleansing agent. (See Chemistry of Cleaxlng.) 



CHAPTER XXXII. 



ORGANIC CHEMISTRY. 



STARCH, SUGAR, ETC. 

Organic chemistry treats of those compounds (composed 
principally of C, H, N, and O, but all containing C and 
H) which are formed chiefly by animals or plants in their 
processes of growth or partial decay. No line can be 
sharply drawn between organic compounds and inorganic. 
Many compounds which formerly were supposed to be 
produced only by the "vital force" of the plant or animal, 
have been formed recently in the laboratory. 



STARCH. 115 



Note. — It is important to remember that we may make two great 
divisions of "organic substances": — 

I. That which is the essential physical basis of life (bioplasm). 

II. That which is essential only in a secondary sense and is used by 
the first in accomplishing its work somewhat as an engine uses fuel, 
water, and the iron rails. ' 

To this second division belong crystalline substances, fats, gelatine, 
cellulose, etc. Between the inorganic and this first division of the 
organic, a distinct line can be drawn. This line bounds all possibilities 
of the laboratory. It is probably within the province of chemistry to 
produce, unaided by the "vital force," all substances in this second 
division. The organic cell proper, with its subtle bioplasm, chemists 
can never hope to form. For example, the chemist's kernel of wheat 
will never grow. (See Spontaneous Ges ekation«ui cyclopaedia.) 

As a rule, inorganic substances have few atoms in the molecule, while 
molecules of organic substances frequently contain a very large number 
of atoms. Often different organic substances contain the same elements 
in the same proportion. This peculiar relation is called isomerism. 

EXAMPLE. 

Butyric acid and ethyl acetate, two well-known compounds, differing 
in essential properties, are isomeric, having the "empirical formula" 
(expressing only the proportions of the elements): C 4 H 8 2 , but the 
"rational formula" (which attempts to represent ?7i some way the arrange- 
ment of the atoms in the molecule) of 

Butyric acid = H C 4 H 7 2 . (Ref. Table No. 2, Continued.) 
Ethyl acetate = C 2 H 5 C 2 H 3 2 . (Ref. Table No. 2.) 

Plants in general prepare food for animals from the 
mineral kingdom, and animals, after using it, return it to 
the mineral kingdom again. The organic by complete 
decay returns to the inorganic. The sun's light and heat 
(Exp. 58) is the motive power by which the plant is ena- 
bled to build up the organic out of the inorganic. 

Starch (C 6 H 10 O 5 ) is a substance found in all cereals, 
in many roots, stems, and fruits. It is composed of grains, 
which the microscope reveals differing in size and shape 
in different plants. These grains swell up and burst on 



•116 CHEMICAL PRIMER. 

heating with water. Its use for food, in the laundry, etc., 
is well known. Arrow-root and tapioca are varieties of 
starch from roots of tropical plants. Sago is starch from 
the pith of the sago-palm. 

The test of starch is iodine, with which it forms a blue compound. 
(Exp. 84.) 

Exp. 131. — Scrape some potato into cold water and squeeze through 
a linen cloth several times. The insoluble starch remains suspended in 
the nitrate, while the woody fiber (cellulose) remains upon the filter. 
After subsidence, pour off the water, and dry. This illustrates the 
method of obtaining starch from the potato. 

When starch is heated to about 205°, it changes into an isomeric com- 
pound, dextrin, much used instead of gum arabic in making adhesive 
stamps. Dextrin is also formed if starch is boiled with water slightly 
acidulated with sulphuric acid. If the boiling is continued longer, the 
dextrin is converted into starch-sugar (C 6 H 12 6 ). Dextrin gives no blue 
color with iodine. 

Gum arabic (C 12 H 22 O n ) exudes from a species of acacia. Peetose 
is a gummy substance found in many fruits and vegetables. 

Cellulose (C 18 H 30 O 15 ), or woody fiber, is the frame- work of the cells 
of plants, and is found in every part, even in the pulpy fruits. Linen, 
made from the inner bark of flax, and cotton — the hollow white hairs 
around the seed of the cotton plant — are nearly pure cellulose. (See 
cyclopaedia. ) If paper is dipped in dilute sulphuric acid (2 vols. H 2 S 4 , 
1 vol. H 2 0) for a few moments, tough parchment paper results. 

Gun-cotton is cellulose, in which part of the H has been replaced by 
the negative radical N0 2 , by dipping in a mixture of HK0 3 and 
H 2 S 4 . It is very explosive. 

Gun-cotton, dissolved in ether (ethyl oxide) and alcohol (ethyl 
hydrate) forms collodion, much used by photographers. 

Celluloid is made chiefly from gun-cotton and camphor, by submitting 
to great pressure. It can be colored in imitation of coral, made into col- 
lars and cuffs, and substituted, in general, for ivory. Its manufacture is 
comparatively a new industry. 

Cane-sugar, sucrose (C 12 H 22 O n ), may be obtained from 
the sugar-cane, beet-root, maple, and certain kinds of. 



STARCH. 117 



palm. In making it from the sugar-cane (1) the canes 
are crushed, (2) lime (Ca O) is added to the juice to neu- 
tralize any acid formed by fermentation, (3) the liquid is 
evaporated to thick syrup, (4) set aside to cool, (5) the 
sugar crystallizes, forming brown sugar, (6) it is put into 
perforated casks to drain. The drainings ("mother liq- 
uor") are molasses. 

In the process of refining, brown sugar is (1) dissolved, 
(2) pumped to upper story of the high building, (3) 
filtered through twilled cotton bags, kept in bath of steam, 
(4)filtered through animal charcoal (Exp. 48), (5) evapo- 
rated in "vacuum pans" (kettles from which air and steam 
are partially removed by pump, so that the syrup boils at 
a lower temperature and does not burn), and (6) set aside 
to crystallize. If in moulds, loaf-sugar results ; if in cen- 
trifugal machines, granulated. The drainings are syrup 
or sugar-house molasses. 

Caramel is sugar carefully "burnt" so that it loses part, but not all, 
of its elements of water. It is used for coloring liquors, flavoring confec- 
tioneries, etc. 

Cane-sugar is not found in animal tissues or secretions, but is 
changed in the alimentary canal before absorption into grape sugar. 
[ Medical students should master all the tests for grape sugar in the Appen- 
dix.] 

Grape-sugar (C 6 H 12 6 ). glucose (dextrose, starch-sugar, fruit-sugar), 
is found in honey, figs, grapes, and many kinds of fruit. It has much 
less sweetening power than cane-sugar. 

Exp. 132. — To a solution of grape-sugar (made by boiling a few 
raisins in water and filtering) add three drops of copper sulphate (5 per 
cent, solution and slightly acidulated with acetic acid), then add strong 
solution of K H (potash or Na H 0, soda) till the light blue color of 
liquid becomes darker. Raise to the boiling point, but do not boil 
beyond a few seconds. A yellowish-red precipitate of cuprows oxide 
(Cu 2 0) falls. This is a delicate test for sugar in animal secretions 
(grape-sugar, or milk-sugar isomeric with cane). (See Add. Exp.) 



118 CHEMICAL PRIMER. 



Exp. 133. -— Divide a solution of cane-sugar into two parts; apply test 
as in Exp. 132, no cuprous oxide falls. Slightly acidulate the second 
portion with H 2 S O i} and boil to syrup. The cane-sugar changes to 
grape-sugar. Dilute and apply test. Yellowish-red Cu 2 falls. — Boil 
for some time a minute quantity of starch in dilute (2 per cent. ) sulphuric 
acid. The starch changes to grape-sugar. Divide into two portions 
and test the first by iodine; no starch is found. Test the second; grape- 
sugar is found. Boil cellulose (woody fiber free from pitch) in dilute 
H 2 S 4 and grape-sugar is found in the solution. 

The insoluble starch laid up in the seeds of plants is 
converted into (soluble) sugar by the action of a nitroge- 
nous substance, called diastase, in the presence of ivarmth 
and moisture. The sugar is then absorbed by the grow- 
ing plantlet, and is built into its structure as woody fiber, 
etc. 



Fermentation is a species of decay. A necessary 
condition is the presence of some nitrogenous ("albumi- 
nous") substance, called a ferment, and the growth therein 
of a fungus plant called yeast This plant is of a low 
order, and spreads by the rapid multiplication of cells 
throughout the whole fermenting substance, if it has the 
needed warmth (about 30°) and moisture. In the fer- 
mentation of substances containing grape-sugar (or cane- 
sugar, which changes to grape-sugar), there are two 
stages: — 

1. The Alcoholic Fermentation, in which the sugar 
breaks up into alcohol and carbon dioxide. 

C 6 H 12 O fi = 2C 2 H 5 HO + 2G0 2 

grape-sugar alcohol caiboii 

dioxide 

2. The Acetic Fermentation, in which, by exposure 
to the air, the alcohol is oxidized, forming acetic acid and 
water. 

C,H 5 HO + 2 = HC.H.O, + H 2 

ethyl hydrate from the acetic acid water 

air 



ALCOHOL, ETC. 119 

A third fermentation called "destructive" (by which the organic re- 
turns to the inorganic) follows the above. The second stage can be pre- 
vented, if the air (oxygen) be excluded from the fermenting material. 
The first stage cannot be prevented "by bottling," provided there is in 
the substance sufficient nitrogenous material (ferment), and provided 
the yeast spores have not been killed by boiling or by an antiseptic. The 
second stage follows the first very rapidly, if the temperature is raised 
(to about 38°, or 100° F). This explains the rapid "souring" of sub- 
stances in hot weather. The fermentation ("working") in preserves 
may be checked by boiling and then excluding the air, thus shutting out 
the yeast spores. 

Beer, ale, etc., are made from malt (grain that has germinated suf- 
ficiently to change nearly all the starch to sugar, and in which the fer- 
mentation has been checked by drying). The malt is crushed, water 
added, and heat applied to turn starch to sugar. It is then cooled, hops 
and yeast are added, when the alcoholic fermentation at once commences. 

Wine is made by the fermentation of grape juice. If all the sugar is 
converted into alcohol and C 2 , dry wine results. If the fermentation 
ceases (from an excess of sugar over the ferment) when only part of the 
sugar is changed, sweet wine results. Effervescing wine is sealed 
in strong bottles while the alcoholic fermentation is going on. In sour 
wine the acetic stage has somewhat progressed. 

When any fermented liquor is distilled, the alcohol (having a lower 
boiling point than water) first passes over through the condenser 
(Fig. 19), together with certain flavoring substances and a certain part of 
the water. Brandy is made by distillation from wine; rum from fer- 
mented cane- juice; whisky from fermented corn, rye, or potatoes; gin 
from fermented barley and rye, and afterwards distilled with juniper- 
berries (flavoring). 

Alcohol (C 2 H 5 H O ethyl hydrate) is the intoxicating 
principle of all varieties of (unadulterated) "liquors." It 
is a colorless, volatile, inflammable, poisonous liquid. The 
medicinal use of alcoholic liquors is the only temperate 
use of them, so the best physiologists and physicians tell 
us. A solution of a substance (medicinal) in alcohol is a 
tincture. (See Volatile Oils.) Strong alcohol contains 
about 10 per cent, water, all of which cannot be removed 



120 CHEMICAL PRIMER. 

by distillation. It may be removed by Ca 0, or some 
other substance which has a great affinity for water, when 
anhydrous, or absolute alcohol, remains. Anhydrous 
(white) Cu S 4 (Exp. 34) is test for absolute alcohol. 
If water is present, the sulphate turns blue. • Strong alco- 
hol is a valuable solvent and antiseptic. 

Common Ether (C 2 H 5 ) 2 0, ethyl oxide, is made by dis- 
tilling alcohol in presence of sulphuric acid. It is a very 
volatile, inflammable liquid. It produces great "cold" by 
its evaporation. If blown in a fine spray (from atomizer) 
upon some part of the body, the rapid cooling produces 
local anaesthesia by " freezing" (chilling) the spot. It is 
inhaled as an anaesthetic, and is a valuable solvent. 

There is a large number of alcohols (hydrates of positive radicals) and 
corresponding ethers (oxides) arranged in series. Methyl alcohol 
(G H 3 H 0, wood spirit) is formed by the destructive distillation of 
wood, and resembles ethyl or common alcohol in many particulars. 
Amyl alcohol (C 5 H n H 0, fusel oil) has a very fetid odor, and is 
much more poisonous than C 2 H 5 H 0. It is formed in small quantities 
in the fermentation of potatoes and grain. Its boiling point is 137°, 
while that of ethyl alcohol is only 78°. The common alcohol is sepa- 
rated from it by fractional distillation, a valuable method of separating 
liquids whose boiling points differ materially. 

The salts of the positive groupings of the ethers, or 
alcohols, are often termed "compound ethers" (Ex.: 
ethyl nitrate, C 2 H 5 N 3 , etc.). Many of these "compound 
ethers" are sold as "essences," and they very closely imi- 
tate the true essences. Ethyl butyrate (C 2 H 5 C 4 H 7 2 ) is 
sold as "essence of pine-apple." 

Chloroform (C H Cl 3 ) is made by distilling alcohol 
with "chloride of lime." It is a colorless, volatile liquid, 
used as an anaesthetic and as a solvent. 



ALCOHOL, ETC. 121 



Chloral (C 2 H C1 3 0), a colorless, oily liquid, is made by passing dry 
chlorine into alcohol. It combines with water of crystallization, form- 
ing a white crystalline substance, the so-called chloral hydrate 
(C 2 H C1 3 H 2 0). Chloral, when taken, reacts with the alkali of the 
blood, producing chloroform and inducing sleep. It is much used in 
medichie . 

Acetic acid (H C 2 H 3 2 , the acid of vinegar), as we have seen, is pro- 
duced by the fermentation, under the proper conditions, of substances 
containing sugar. It is produced in the second stage by the oxidation of 
alcohol. Strong acetic acid crystallizes at 17° and is called glacial. 
The * 'mother" of vinegar is a fungus plant; it assists the fermentation 
by absorbing from the air and giving it up to oxidize the alcohol. 
When the alcohol is all gone, however, it works mischief. The vinegar 
itself is oxidized and destroyed (destructive fermentation). Sulphuric 
acid and pungent spices are often added to vinegar to increase its 
strength. One gallon of sulphuric acid in a thousand gallons of vinegar 
is used to prevent the destructive fermentation. A large quantity of 
H 2 S 4 , however — such as is added by some unscrupulous dealers to 
make weak vinegar strong— is exceedingly injurious. 

Carbolic acid (C 6 H 5 H O, phenyl hydrate), better classed 
with the alcohols (of phenyl series), is obtained from coal- 
tar. It is a very poisonous liquid (it may be obtained 
crystallized) and is a powerful antiseptic and disinfect- 
ant Carbolic acid is sometimes confounded with creosote 
(C 8 H 10 O 2 ), the antiseptic principle of smoke (by which 
"bacon," etc., is "cured"); indeed, impure carbolic acid is 
commonly called creosote. (See Antidotes.) 

Benzol (CeHsH, phenyl hydride — see Illuminating Gas) is a very 
volatile, inflammable liquid, is a valuable solvent, and is used to remove 
grease spots from silk and woolen articles. From it, by the action of 
nitric acid, nitrobenzol (C 6 H 5 N" 2 ), an oily liquid is prepared. By the 
action of reducing agents upon nitrobenzol the celebrated aniline 
(C 6 H 7 N), the source of the "coal-tar" dyes, is prepared. (See Dyeing.) 

(For tar, coal-tar, naphtha, benzine, kerosene oil, dead-oil, petroleum, 
bitumen, etc., see cyclonsedia. ) 



122 CHEMICAL PRIMER. 



There are three great classes of organic foods : — 

1. Starch, sugar, and allied bodies. 

2. Oleaginous substances. (See Chap, xxxiv.) 

3. Albuminous substances ("nutritious matter," nitrog- 
enous matter). 

Albumen (formula very complex, composed of C, H, N", S, and 0) is 
found nearly pure in white of eggs. Albuminous matter possesses the 
power of (1) becoming a ferment, (2) of coagulation, and (3) of putrefac- 
tion. Casein is found in milk, and is coagulated by rennet (acid); 
gluten, in flour, meal, etc.; fibrin, in blood, and another variety of 
fibrin in muscular tissue. (Medical students see Add. Exp. for tests.) 

Exp. 134. — Soak a small, clean bone over night in H CI (30 per cent.). 
The mineral matters are dissolved, and the soft animal matter left. 
Wash thoroughly in water and leave in water over night again. Boil 
the animal matter for some time in a small quantity of water and set 
aside to cool. A gelatinous substance remains. 

Gelatin (formula complex; a nitrogenous substance not belonging to 
albuminous matter proper) is formed by the action of hot water upon 
animal membranes, tendons, and bones. Glue is very impure gelatin. 
Isinglass is a very pure gelatin from the air-bladders of fish. (The 
mineral, mica, used in the doors and sides of parlor stoves, is often im- 
properly called isinglass.) 

CHEMISTRY OF COOKING. 

Flour consists of gluten, starch, and a little dextrin 
and sugar. The oily and mineral substances are con- 
tained chiefly in the bran of grain, hence "coarse food/' 
as corn meal, graham flour, oatmeal, cracked wheat, etc., 
are very necessary for the proper development of bone 
and sinew. 

In bread-making the flour, mixed with milk (or water) 
containing yeast, is set in a warm place, and immediately 
the alcoholic fermentation begins. The carbon dioxide 
set free is held by the gluten, causing the dough "to rise." 
This is kneaded, to distribute evenly the fermentation and 
to break up the large bubbles of C 2 . 



CHEMISTRY OF COOKING. 123 

In baking, the C 2 and alcohol escape. If the oven 
is too hot, a crust forms too quickly, prevents the escape 
of the C 2 , and large cavities are formed. If the fire 
is not hot enough, the C 2 escapes before the cells are 
sufficiently hardened, and the bread falls. Sour bread is 
formed when, before (or while) baking, the second stage 
(acetic) of fermentation is reached. The acetic stage 
follows the alcoholic very rapidly if the temperature of 
fermentation is high. (See Notes under Fermentation.) 
A very slow fire in baking may produce the same result. 
Saleratus (H K C 3 , or soda HNaC 3 , acid salts, but 
these have alkaline reaction), is added to neutralize any 
acid that may be formed by this second fermentation. 

In raising biscuit, "soda" and "cream of tartar" 
(H K CiH^Og) are used to furnish the C 2 , while the salt 
that remains is a harmless one. 

Common baking powder is merely "cream of tartar" 
and "soda," but it is often adulterated with alum, to make 
inferior flour look white. Bread containing alum is 
highly injurious, producing chronic constipation. (See 
test, Add. Exp.) 

"Yeast cakes" are made by exposing moistened corn 
meal (or other similar substance) containing a ferment, to 
moderate temjoerature till the gluten is in the midst of the 
alcohol fermentation. The fermentation is then checked 
by drying. The yeast plant (fungus) throughout the 
cake may be likened to so much dry seed, which needs 
only to be sown in the right soil (in the dough). 

The chemical changes in the body (Physiological 
Chemistry) are too difficult for insertion in a primary 
work. 



124 CHEMICAL PRIMER, 



CHAPTER XXXIII, 



VEGETABLE ACIDS AND BASES (ALKALOIDS). 

Compounds of oxalic acid (H 2 C 2 4 2 H 2 0), especially 
K 2 C 2 4 , and Ca C 2 4 are found in rhubarb, sorrel, etc. 
(also a very little of the free acid). The acid is a power- 
ful poison. It is sold as "salts of lemon" (a dangerous 
name), to remove ink stains. It used to be very expen- 
sive, but it is now made on a large scale by heating saw- 
dust and caustic potash (K H O). (See Antidotes and 
Chemistry of Cleaning.) 

Salts of tartaric acid (H 2 C i H i 6 ) ) also minute quanti- 
ties of the free acid, exist in many fruits, and especially 
in the grape (as acid potassium tartrate, H K CJE 4 6 , see 
Acid-salts). It settles during fermentation, forming 
a crust ("argol," "bitartrate of potash") which, when 
purified, is cream of tartar (H K C 4 H, 6 ). Tartar 
emetic is a double salt: potassium antimonyl tartrate 
(K Sb~0 CJI7o 6 ). Rochelle salt is K Na C 4 H, 6 . 

Citric acid (H 3 C 6 H 5 7 H 2 0) is the acid of the lemon, 
lime, etc. Its salts are also present. 

Malic acid (H5,CJE 3 5 ) occurs (together with potassium 
malate) in most unripe fruits, especially unripe apples. 

Tannic acid (H 3 C 27 H 19 17 — tribasic ?), or tannin, is 
found in the leaf and bark of most trees and of many 
shrubs (oak especially, in nut galls, hemlock, etc.), together 
with a little gallic acid (H,C 7 HA, H 2 0). 



THEORY GF TYPES. 125 



Exp. 135.— To a solution of tannic acid add a solution of gelatin (from 
Exp. 134); a yellowish- white precipitate of gelatin tannate falls. 

In the process of tanning, the tannic acid unites with 
the gelatin of the hide, forming a tough compound 
(leather). 

Exp. 136. — To a solution of tannic acid add copperas solution. Ink 
is formed, becoming darker by exposure to the air. (Ous salts of Fe 
have a tendency to oxidize and form peculiar and, as a rule, less soluble 
"oxy-salts"). 

3FeSO, + 2H 3 C 27 H 1S 17 = Fe 3 2 C 27 H 19 17 + 3 H 2 S 4 

copperas tannic acid INK corrodes pens 

Leather is blackened by washing one side with solution 
of iron sulphate, thus covering it with ink. Carbolic acid 
or corrosive sublimate (Hg Cl 2 ), antiseptics, are used to 
keep ink from moulding. 



The alkaloids are organic bases (see comments, Exps. 
4 and 5), and they form salts on the ammonia type. 
Many of them have a bitter taste, are powerful poisons, 
and valuable medicines. (See Antidotes.) The liquid 
alkaloids (few) contain C, H, and N, while the solid 
(nearly all) contain C, H, N, and O. Their salts occur 
in the plants from which they are obtained. 



THEORY OF TYPES. 

The theory of types has done much to advance the science of chemis- 
try. The pupil, however, must distinguish between theory and fact. 
The formation of compounds on the water-type is strictly represented 
thus : — 

tt = water -it = nitric acid 

±1 I ±1 | 

in which the negative radical, nitryl (N 2 ), replaces an atom of H in 
the molecule of water. So: — 

u I SOI 

* 2 2 = two molecules of water, tt' 2 2 = sulphuric acid 



126 CHEMICAL PRIMER, 

in which two atoms of H in the water have been replaced by the negative 
radical sulphuryl, S 2 . The reaction in Exp. 16, written strictly to 
represent the water- type, becomes: — 

Na I Q , C,H 3 I Q _ C 2 H 3 I Q . H I 
H I ° T H J U - Na I ° T H | ° 

It is easily seen how the negative radical, usually considered by 
chemists as the replaceable and replacing quantity in reactions, is 
obtained from the negative l 'grouping," viz.: by subtracting one atom 
of from monad groupings, two from dyad groupings, etc. Negative 
radicals usually take the termination, yl. 

Again, binary acids and salts cannot in any strict sense be referred to 
the water-type as in this book, but must be referred to the hydrochloric 
acid type. 

The formation of compounds on the ammonia type is shown in the 
following formulas, the connecting element being the triad, nitrogen. 
The examples given are artificial compounds (alkaloids): — 



H 
H 
H 



N = 



C 2 H 5 

C 2 H 5 

H 



C 6 H 5 


phenyl- 


C,H 5 




ammonia H 


N amine 


H 


N ethyl-amine 


H 


(aniline) 


H 





C 2 H 5 

N diethyl-amine C 2 H 5 
C 2 H 5 



N triethyl-amine 



If the H of ammonia (one or more atoms) is replaced by a positive 
radical, an amine results; if by a negative radical, an amide; if a posi- 
tive and a negative both take part in the replacement, an alkalamide — 
all giving rise to very hard names. 

The ammonia type should be considered only in this 
respect by beginners. Ammonia forms salts with the 
acids, without replacing the hydrogen of the acid. The 
alkaloids do the same thing. 

EXAMPLES. 

H 3 N + H CI = H,]Sr CI or H 3 N H CI = chloride of ammonia 

C 6 H 7 K + HC1 = C 6 H 7 NHC1 — chloride of aniline 

( chloride or 
C 17 H 19 N 3 + H CI = C 17 H 19 N 3 H CI, 3H 2 = ] hydrochlorate 

water of ! of morphine 

crystallization * *■ 



ALKALOIDS. 127 



Morphia (C n H 19 N 3 , H 2 0), or morphine, is the prin - 
cipal alkaloid in opium, the dried j nice of the poppy. In 
small doses it acts as a sedative; in large doses, as a nar- 
cotic poison. It is combined with meconic acid in the 
plant as meconate of morphia. A salt of morphia (sul- 
phate or chloride, usually) is sold at the drug stores as 
1 'morphia," and the same is true of many other alkaloids. 
Laudanum is tincture of opium ; paregoric, a camphora- 
ted tincture, flavored with aromatics. Many patent con- 
coctions for ''soothing" children contain opium, and are 
very pernicious, 

Quinia, or quinine (C 20 H 2i N 2 O 2 3 H 2 0), is obtained from 
the bark of the cinchona, a tree found native in Peru. It 
is largely used in medicine, especially in fevers It has a 
bitter taste. In large or long continued doses it is apt to 
impair the hearing. 

Aconitia, or aconite (C 5i H iw N 2 ), is obtained from 
aconite leaves and root. It is used in fevers to cause per- 
spiration (sudorific). It is one of the most violent poisons 
known. 

Strychnia, or strychnine (C 21 H 22 N 2 2 ), is the alkaloid 
in nux vomica (seeds) and the St. Ignatius bean. It is 
also one of the most poisonous of the alkaloids. It is 
largely used in medicine as a nervous tonic It is in- 
tensely bitter. 

Atropift (C 17 H 23 N 3 ) exists in belladonna, or Deadly 
Nightshade, as malate of atropia. 

Mcotia, or nicotine (C 10 H U N 2 ), is the volatile liquid 
alkaloid of the tobacco plant. It is intensely poisonous. 
As a rule, it stupefies and clouds the intellect, especially of 
persons not full grown. Those boys who are great smokers 
rarely take a high standing in their classes. 



128 CHEMICAL PRIMER. 

Cocaine is an alkaloid obtained from the dried leaves of 
the Coca shrub (erythroxylon coca), a native of Peru and 
Bolivia. It is a powerful anaesthetic^ 

The alkaloids are very numerous, as are also the vegetable acids. 
For fuller account of each see cyclopaedia, also see Antidotes. [Med- 
ical students should master the tests in Appendix.] 



CHAPTER XXXIV. 



OILS, FATS 5 RESINS, ETCo 

There are two great classes of oils: Fixed and Volatile 
(or Essential). Fixed oils cannot be distilled without 
decomposition into various hydrocarbons. Volatile oils 
can be readily distilled. 

Fixed oils are salts (using the term in a wide sense). 
Hard fat is principally glyceryl stearate ("stearin"), soft 
fat, glyceryl palmitate ("palmitin"), and liquid fat, glyc- 
eryl oleate ("olein"). Fixed oils, when boiled with an 
alkali (K, Na ? etc., hydrate), react with the alkali to form 
a "soap,' 5 and "glycerine^ 9 (Table No. 2.) 

Exp, 137= — Mix a strong solution of "caustic soda" (Na H 0) with 
olive oil and boil for about twenty minutes. 
3NaH0 + C 3 H 5 3C 18 H 3 A =: 3 Na C l8 H 33 2 + C 3 H 5 3 H O 

sodium glyceryl oleate sodium oleate glyceryl hydrate 

hydrate (olive oil) (hard soap, because it is (glycerine) 

not a deliquescent salt) 

Add a little of solution of common salt. (Soap does not dissolve in 
salt-water, ) Set aside tc cool, the soap and glycerine separate. 

Olive oil contains some glyceryl palmitate, so that the 
soap is partly sodium palmitate. If tallow be taken in 
place of olive oil, the soap is principally sodium stearate. 



GILS, FATS, RESINS, ETC. 129 



Inspection of the reaction reveals the whole story of soap- 
making. If "caustic potash" is taken, the reaction be- 
comes 
3 K H O + C 3 H 5 3 C 18 H 33 2 = 3 K C 18 H 38 2 + C 3 H 5 3 H O 

caustic potash glyceryl oleate soft soap, because glycerine 

potassium oleate is 
a deliquescent salt 

Potassium forms a soft soap and sodium a hard soap. 
Ca forms an insoluble "lime soap." Mg also forms an 
insoluble soap. Insoluble soaps are sometimes used in 
medicine and in the arts. Solutions of soluble soaps (K 
and Na) are good solvents of the cuticle and of many 
forms of "dirt," and hence are valuable cleansing agents. 
They must be used, however, with soft water, or there 
is a great waste of the soap. If soft soap, for instance, 
is put into hard water (e. g., containing Ca S 4 , or other 
soluble sulphate), the soap is destroyed, and an insoluble 
"lime soap" formed by the following reaction: — 

Ca S O, + 2 K C 18 H 33 2 = K 2 S 0, + Ca 2 C 18 H 33 2 

soft soap insoluble lime soap 

A similar reaction takes place if the water is only of 
temporary hardness. (See Exp. 33.) Water of tempo- 
rary hardness, as we have seen, is softened by boiling. 
Water of permanent hardness may be softened (for wash- 
ing purposes) by adding borax (Na 2 B 4 7 ), or washing soda 
(Na 2 C 3 , 10 H 2 0). If the last, 

CaSO, + Na 2 C 3 = Na a SO, + Ca C 3 

cause of (remaining in sulu ion precipitate 

hardness but not affecting 

the soap) 

In making "lye" from wood ashes, the ashes are 
leached in a large tub containing "lime" (Ca 2 H O) at 
the bottom. The K 2 C 3 of the ashes is carried by the 
hot water down through lime, and the reaction is: — 

Ca 2 H O + K 2 C 3 = 2 K H + Ca C 3 

9 " lye " 



130 CHEMICAL PRIMER. 

If no lime is used, of course the lye is potassium carbonate (impure 
solution), and in making soap from K 2 C 3 we have (if olive oil is used) 
[Don't try to remember reaction.] 

3K 2 C0 3 + 3H 2 + 2C 3 H 5 3C 18 H S3 2 = 

V 

6KC 18 H 33 2 + 2C 3 H 5 3HO + 3 C 2 

soap glycerine 

Soap usually contains an excess of the alkali. Home-made soap con- 
tains both alkali and glycerine and is very variable in its composition, 
containing several fat acids united to the alkali. Soap is insoluble in 
salt-water and hence separates if salt be added to the "suds." 

' 'Stearin' 5 candles are made (chiefly) of stearic acid by decompos- 
ing the tallow by superheated (285°) steam. 

3H 2 + C 3 H 5 3 C 18 H 35 2 = 3HC 18 H 35 2 + C 3 H 5 3HO 

steam. tallow stearic acid glycerine 

(stearin candles) 

There are two great classes of fixed oils, drying oils and 
non-drying oils. A drying oil (as linseed oil, i. e., flax- 
seed oil), when exposed to the air, oxidizes to a hard res- 
inous substance. A non-drying oil does not oxidize to a 
resinous body when exposed to the air, but instead suffers 
a fermentation that sets the acid of the oil free, that is, 
the oil becomes "rancid." For instance, the purest olive 
oil is not entirely free from nitrogenous material, and 
fungus germs, creeping in, cause the following reaction : — 
C 3 H 5 3 C 18 H 33 2 + 3 H 2 = 3 H C 1S H 33 2 + C 3 H 5 3 H O 

olive oil moisture oleic acid glycerine 

from air 

As we have seen, glycerine (C 3 H 5 3 H O) is a "by- 
product" in the manufacture of soap. Glycerine is 
classed by chemists as an alcohol. It is a viscid, sweet 
liquid, a good solvent, and a valuable antiseptic. It is 
useful in dressing wounds, because it is not volatile, but 
protects from the air and keeps the part moist. Glycer- 
ine, treated with nitric and sulphuric acids, becomes the 
fearful explosive nitro-glycerine (C 3 H 5 3 N 3 , glyceryl 
nitrate). 



CHEMISTRY OF CLEANING. 131 



CHEMISTRY OF CLEANING. 

The soaps stand first in the list of cleansing agents, their solution in 
soft water (preferably hot) dissolving or forming emulsions with oily 
substances. The sebaceous glands of the skin secrete oleaginous matter 
to keep the skin soft and pliable (there is also oily matter in the perspi- 
ration). This oil, with accompanying "dirt," being absorbed by the 
clothing prevents water alone from cleansing the material, as "oil and 
water will not mix." 

Solutions of caustic potash and caustic SOda form emulsions with 
oils even more readily than soaps do, but they corrode the skin and are 
apt to injure the cloth as well. Dilute solutions are used to clean win- 
dow glass, greasy tins, etc. 

Wood ashes (which contain potassium carbonate) are used with 
water to cleanse bottles and coarse utensils. Solutions of potassium 
carbonate operate like solutions of caustic potash only with much less 
intensity. 

Ammonia water is the best agent for cleaning glass and (purified) 
for cleansing woolens and for the bath, also very dilute for hair brushes. 

Sal soda (washing soda, sodium carbonate) is used to soften hard 
water (see above) and also is useful with soft water. In the latter case 
not over two ounces (first dissolved) should be added J:o a large tub of 
water. It injures the skin if too strong z nd does not cleanse so effect- 
ively. So-called "washing compounds" are composed principally of 
sodium carbonate. 

Solutions of borax are excellent to cleanse delicate and colored fab- 
rics. They also soften water permanently hard (see above). 

To dissolve oily spots, benzine (a volatile oil from petroleum), fresh, 
pure turpentine, alcohol, and ether are used. Solid absorbents are often 
to be preferred to remove spots from paper, carpets, etc., such as mag- 
nesium carbonate, powdered soapstone, and buckwheat flour. These 
should be several times thoroughly rubbed into the carpet or upon the 
paper and then brushed out or off again. 

Grass stains are removed (while fresh) by dissolving in absolute alco- 
hol. Fruit stains are washed away by pouring on boiling water, or^ if 
this fails, by solution of oxalic acid. 

Iron rust (red) is best removed by several applications of hot, very 
dilute hydrochloric acid, soluble chloride of iron being formed by 
"change of partners." Thoroughly wash afterward with water. "Sol- 



132 CHEMICAL PRIMER. 

uble blues" are composed principally of iron ferrocyanide (Prussian 
blue), and clothes should be thoroughly rinsed to remove the alkali, or 
iron rust stains appear by decomposition of the "bluing." 

Ink (black iron stains) is removed by solution of oxalic acid, chemi- 
cal reaction by "change of partners" gives iron oxalate and tannic acid. 
Immediately and thoroughly wash out with water and filially with very 
dilute ammonia water, else a yellowish tannic acid stain is left. 

Oxalic acid is also an excellent agent for cleansing brass, removing 
"shoe-leather" stains, etc. 

Fumes of burning sulphur (S 2 , which see) will often remove col- 
ored spots when nothing else will. 

Acetic acid added to the second rinsing water will restore perfectly 
the color (if from "coal-tar" dye) of bright blue flannels or other fabrics 
that fade somewhat in washing, because the soap neutralizes partially 
the acid contained in the dye. [See "Ammonia Water," page G2.] 

Coarse scouring 1 agents are easily obtained, but for silver and arti- 
cles of value, the best polishing agent is, perhaps, precipitated chalk. 
Five cents' worth of quicklime and ten cents' worth of hydrochloric 
acid by the process of Exp. 33, will precipitate sufficient to last for a 
long time. The water used should be filtered, and after quicklime is 
slacked, the clear lime water should be carefully drawn off by siphon so 
as to exclude all gritty sediment. After precipitation carefully dry and 
preserve. Many polishing agents, for a tablespoonful of which twenty- 
five cents is asked, are principally, if not entirely, precipitated chalk. 
Most "tooth powders" are simply precipitated chalk (colored and per- 
fumed). 

& 

Volatile oils (or Essential oils) are of vegetable origin. 
They exist in the petals of flowers, in leaves (of mint), in 
seeds (of carraway), in rind of fruit (of orange, lemon) 
and in the root (of sassafras). They are usually obtained 
by distilling with water (passing steam over), from the 
part of the plant containing them. They do not make 
soaps. Their 'solution" in alcohol is called an essence. 
Adulteration with a fixed oil is easily discovered by evap- 
orating on white paper and noticing that a grease spot is 
left. 



ANTIDOTES. 133 



Oil of Turpentine (C 1G H 16 "spirits of turpentine") is obtained from 
the "pitch" of pines by distillation. It is an excellent solvent, dissolv- 
ing the resins to form varnishes. A large class of volatile oils are pure hy- 
dro-carbons, many having the same empirical formula with oil of turpen- 
tine, though widely different in properties. 

Of a second class Camphor (C l0 H 16 O) is a type, as oil of bitter almonds, 
cinnamon, spearmint, etc. These all contain 0. 

A third class of "strong smelling" volatile oils contain S. Ex: Oil of 
mustard, horse-radish, onion, etc. 

A resin is an essential oil oxidized. ("Rosin" is the resin of tur- 
pentine.) A balsam is an oleo-resin, i. e., a resin dissolved in a vola- 
tile oil, or a volatile oil partially oxidized. If a balsam is distilled, the 
essential oil passes over, leaving the resin behind. Shellac is a resin 
obtained from lac, the juice of an East India tree. (See Appendix.) 
Amber is a fossil resin. 

Gum resins are milky exudations from many plants, which afterward 
solidify in the air. Chltta-percha is obtained from the juice of an East 
India tree, as is also gum-benzoin, the chief source of benzoic acid 
(H C 7 H 5 2 ). India-rubber (caoutchouc) is the solidified juice of cer- 
tain tropical trees. Vulcanized rubber is made by heating the rubber 
with sulphur (Goody ear's patent). 



CHAPTER XXXV. 



ANTIDOTES. 



When a person is taken suddenly and violently ill after eating some- 
thing, poisoning may be suspected. By careful attention to this chap- 
ter it is more than possible that some member of the class may be able 
to save a human life. 

A poison is a substance which, if introduced into the 
animal system, may produce morbid or deadly effects. 
We give antidotes, either (1) to get rid of the poison at 
once (by means of an emetic, or cathartic — a mechanical 



134 CHEMICAL PRIMER. 

antidote), or (2) to hinder its absorption (as when we give 
a chemical antidote to form an insoluble compound with 
the poison — see Exp. 12), or (3) to counteract its effect (as 
when we give stimulants for the poison of serpent bites, 
for narcotic poisons, etc.). 

Exp. 13S. — Shake up thoroughly the white of au egg in a bottle half 
filled with water and filter. The filtrate is a solution of albumen. 
Arrange test tubes containing very slightly acid solution of soluble com- 
pounds of Hg (corrosive sublimate), Cu. Zn, Sn, Fe (copperas), Ag( ni- 
trate), [Pb and Ba] respectively. Into each let fall two o*- three drops 
of albumen solution. Insoluble compounds of albumen and the metal 
(formula too complex to be written) are precipitated. [Notice that with 
Pb and Ba compounds the precipitate does not readily appear and anti- 
dotes below are to be relied upon.] 

Albumen (milk, flour and water, and especially raw 
eggs) is an excellent chemical antidote for most metallic 
salts. As precipitates are not absolutely insoluble in the 
stomach, they should be immediately removed by an 
emetic. 

The best emetic is the common one, "mustard" (a tea- 
spoonful in a cup of — preferably warm — water). When- 
ever poisons are to be removed by an emetic, warm water 
should be freely drank to rinse out the stomach thor- 
oughly. Oils (fats, butter, and lard) and mucilaginous 
drinks (as flaxseed tea) are always beneficial and should 
be freely given immediately, and for treatment afterward. 
In general, whatever would be good treatment for a 
burned, bruised, or injured skin, is good treatment for 
the mucous membrane of the alimentary caned, burned 
or irritated by some poison. 

If silver nitrate or corrosive sublimate are strong, the antidote must be 
given within a few seconds, or the poison wiU have done its worst, and 
recovery, if it takes place at all, must depend upon after treatment. .A 



ANTIDOTES. 135 

rather large dose of a mild cathartic (as castor oil) should be used instead 
of the emetic whenever solution of either sublimate or nitrate has been 
taken. The best antidote for silver nitrate is salt and water, as we have 
inferred from Exp. 6, though albumen is about as good. 

If the other metallic salts (except, see cyanides below) have been 
swallowed, especially in the solid state (powder), the antidote may be 
given later (from ten to twenty minutes) with hope of its doing good. 
But the danger rapidly increases with the lapse of time. 

Most salts of Zn and Sb (also Cu S 4 ) are fortunately emetics them- 
selves, but if vomiting does not occur, prompt action must be resorted 
to. The best antidote for zinc, copper, or iron sulphate is a careful dose 
of sodium carbonate, "washing soda" (followed by emetic). 

Zn S 0, + Na, C0 3 - Na 2 S 0, + Zn C 3 

insoluble 

The best antidote for "arsenic" (or Sb) is fresh, moist ferric hydrate, 
Fe 2 6H0. It is best precipitated when needed by mixing ferric chlo- 
ride solution (liquor or tincture) with slight excess of dilute ammonia 
water. An insoluble ferric arsenate (Fe 2 2 As OJ is formed in the stom- 
ach. Chalk, oil, milk, or mucilaginous drinks may be given to envelop 
the particles of As 2 3 mechanically, if it has been taken in the solid 
form; but the thing to be depended upon ordinarily is the emetic, followed 
by purgative (castor oil). 

A careful dose of potassium f errocyanide is a good antidote for copper 
compounds, as Cu 2 Fe (C N) 6 is insoluble (give emetic). 

Magnesium sulphate (Epsom salt, Exp. 12) is the best 
antidote for lead and barium compounds (with emetic). 

A careful dose of ammonium carbonate is the best antidote for tin 
compounds (with emetic). 

Example: — 
Sn*Cl 2 + (H^ T ) 2 C0 3 + H 2 = 2 H 4 N CI + Sn 2 H + C 2 

precipitate 



The antidote for acids (sulphuric, nitric, hydrochloric, 
etc.) is magnesium carbonate (see Reaction, Class 4), 
chalk, lime-water, or soapsuds. The antidote must be 
given within a few seconds if the acids are strong. 



136 CHEMICAL PRIMER. 



For oxalic acid, lime-water (Exp. 15, or chalk) is the best antidote. 
Prussic acid (H C N) and other cyanides require stimulants, as cold 
douche to the spine, dilute ammonia water inhaled and ammonium car- 
bonate given in small doses (see snake poison below). If prussic acid is 
strong there is no antidote. Give no emetics with acids (unless acid 
is very dilute), but administer oil (olive) freely. 



The antidote for .alkalies (caustic potash, "lye," caus- 
tic soda, etc.) is a dilute acid, preferably the most common 
one vinegar (acetic). 

KHO + HC. 2 H 3 0, = KC 2 H 3 2 + H 2 

soluble but 
harmless salt 

Or tartaric acid, "cream of tartar," citric acid (lemon juice), etc. If 
these are not at hand and the mineral acids are given, the acid must be 
very dilute and given sparingly. .4??. overdose would he substituting one 
■poison for another. (For caustic baryta, Ba 2 H 0, or for lead hydrate, 
see above.) 

If the caustic alkalies are strong, the antidote must follow in a few 
seconds, or it will be of no avail. Give no emetic with alkalies. 



For narcotic poisons (as opium, morphine, cholera 
medicines, "soothing syrups") and the alkaloids in gen- 
eral, the emetic is to be relied upon chiefly, though tan- 
nic acid (strong tea or coffee) may be given, as it forms 
an insoluble compound with many alkaloids. 

The narcotic poisons require in addition to the emetic, stimidants 
(strong coffee, brandy, careful dose of ammonium carbonate) and vigor- 
ous efforts to leep the patient awake. Strong coffee is especially useful in 
cases of opium poisoning, as it acts as a powerful stimulant to the nerve 
centers affected by opium. Aconite calls for stimidants. Stryclinine re- 
quires above all the emetic, also the inhalation of chloroform cr ether to 
check spasms. Patient must be kept as qitiet as possible. 

The emetic should be promptly given in case of poisoning by un- 
healthy fish or meat. Oils should follow (and paregoric in severe 

cases). 



ANTIDOTES, 137 



Phosphorus poisoning requires the emetic and mucilaginous drinks 
with magnesium hydrate (best precipitated when needed by adding 
ammonium hydrate to slight excess of magnesium sulphate solution), 
followed by large doses of the cathartic (purgative) castor oil. 

It is not generally known that "carbolic acid" (re- 
member that this is not an acid proper, but an alcohol) is a 
more dangerous poison than strychnine. Strychnine kills 
''deliberately" and with a smaller dose, but carbolic acid 
does its work quick. Strychnine gives time (10 to even 
30 minutes) to hunt up antidotes, or call a physician ; but if 
a teaspoonful of strong carbolic acid is taken, usually no 
remedy will save a life after twenty seconds have elapsed. 
As it is frequently used in sick rooms for bathing pur- 
poses (diluted), its well known odor is no protection in 
such cases. Olive oil (butter, lard, etc.) freely given, fol- 
lowed by castor oil (cathartic) is its best antidote. Give 
no emetic, unless acid is quite dilute. 

For the bite of poisonous serpents (poison, a powerful sedative), 
stimulants, as alcoholic liquors, but best of all, ammonium carbonate (a 
teaspoonful of 10 per cent, solution, which may be carried in a small 
vial, tightly corked, in the vest pocket) should be taken within a few sec- 
onds. The dose of ammonium carbonate should be repeated twice at 
intervals of ten minutes. If possible, the wound should be immediately 
cauterized (by nitric acid, caustic potash, or hot wire), or ligature put 
about the limb above, and the poison sucked out from the wound (the 
poison is harmless in the stomach). 

Note. — The pupil will notice that in most cases of poisoning the 
emetic is given. He should charge his memory with the few excep- 
tions, acids, alkalies (also silver nitrate, corrosive sublimate), and car- 
bolic acid, and give emetics in all other cases. To receive poisons into 
an empty stomach is most dangerous. In a full stomach the poison is 
diluted and the absorption is slow, so that rapid filling of the stomach 
with almost any liquid food would be better than nothing. Especially 
would milk and mucilaginous drinks be useful dilutents, to say nothing 
of their soothing action. A physician should be called in all cases of 
serious poisoning to direct the after-treatment. 



138 CHEMICAL PRIMER. 



The following statements about poisons should be care- 
fully studied and observed at your homes: — 

1. Poisons should never be left within the reach of 
children. 

2. They should be kept by themselves, apart from non- 
poisonous medicines. 

3. They should be kept plainly labeled as poison. 

4. Any substance in an unlabeled bottle should be 
promptly destroyed. 

5. Whenever a poison is bought, its antidote should be 
bought, placed beside it and plainly labeled (as to the 
proper dose, if antidote in excess would be injurious). 

6. After this last is done it should be remembered that 
"an ounce of prevention is worth a hundred pounds of 
cure." 



MISCELLANEOUS QUESTIONS. 

1. Matter exists in what three physical states? 

2. The atomic theory divides matter how? 

3. Atoms of different elements differ in what three essential respects? 

4. Define compound radical, acid, base, salt, precipitate, reagent, 
filtrate, sand bath, water bath, alkali, sublimation. 

5. What is "soda water"? Davy's safety lamp? a deliquescent sub- 
stance? a condenser? a pipette? oil of vitriol? aqua regia? 

6. How much mercury in 150 grams of mercuric sulphide (use tables)? 

7. How much lead will be required to make 250 kgs. of lead carbon- 
ate ? How much to make 25 grams of Pb ? 

8. How much silver nitrate was in a solution from which 30 gms. of 
silver chloride was precipitated? 

9. Write formulas for ferric oxide, cuprous oxide, mercuric nitrate, 
ferrous sulphide, cupric chloride, aluminum oxide, mercurous iodide, 
stannic chloride, ferrous sulphate, and ferric sulphate? 

10, Reaction when calcium carbonate and citric acid are united. 

11. Reaction in making oxygen, hydrogen, carbon dioxide, hydrogen 
sulphide, hydrochloric acid, and sulphur dioxide. 



MISCELLANEOUS Q UESTIONS. 1 39 



12. How many litres of can be made from 300 gms. of potassium 

chlorate? (A litre of H weighs .0S96 gms.) 

13. If we obtain 500 litres of C 0>, how much calcium carbonate was 
used? How might the druggist make Cu C 4 H 4 6 ? 

14. Tell what you know of S 0., (3 lines), of oxygen, of nitrogen. 

15. Tell what you know of H 3 S, of H, of C 0,,"of CI, of C N. 

16. What is glass? How annealed? How colored? How etched? 

17. How might you tell whether or not a white powder was As 2 O a ? 

18. Give Marsh's test for "arsenic." How told from antimony? 

19. What is an alloy? an amalgam? metal? "paste" diamonds? 

20. What three methods of '•mining for gold?'* and tell much more 
about each than you find in this Primer (10 lines). 

21. For what is platinum used? phosphorus? borax? mercury? 

22. What would you do if you had taken by mistake nitrate of Ag? 

23. How would you test for decomposing organic matter? 

24. Why can some metals be cast, while others cannot ? 

25. What is "white lead," and how made? What is mosaic gold? 

26. What is the antidote for lead acetate? barium hydrate? carbolic 
acid? corrosive sublimate? oxalic acid? phosphorous? 

27. Give Bessemer's process for making steel. Leblanc's process for 
Na 2 C 3 . How would the druggist make calcium citrate? 

28. What is "galvanized iron?'' "tinware?" quicklime? plaster of 
Paris? quartz? a "base metal"? an oxidizing agent? 

29. What is fusible metal? indelible ink? gelatin? leather? 

30. Difference between water-slacked and air-slacked lime? 

31. Give reaction in making soft soap (use Table); hard soap. 

32. How is brown sugar refined? Xame^re prominent alkaloids. 

33. Reactions in alcoholic and acetic fermentations (C 6 H 12 6 sugar). 

34. Why is soap wasted when hard water is used in washing? 

35. What is a resin? rosin? a balsam? tincture? essence? soap? 

36. What would you do if one had taken an overdose of morphine? 

37. In what cases of poisoning should no emetic be given? 

38. What makes the bread "rise?'' Explain fully. 

39. Name all the antiseptics mentioned in this book. 

40. Xame the disinfectants; the anaesthetics; the bleaching agents. 






UO CHEMICAL PRIMER. 



APPENDIX. 



SECTION A. 



NORMAL SALTS, ACID SALTS, ETC. 

A normal salt (old name neutral salt) is one which is 
formed by replacing all the replaceable hydrogen of the 
acid by a positive element or grouping. 

EXAMPLE. 

H 2 C 4 Hi 6 = hydrogen tartrate = acid. 

K 2 C 4 11^ 6 = potassium tartrate = normal salt. 

Note. — Hitherto by salts have been meant normal salts. 

An acid salt is one which is formed by replacing only 
part of the replaceable hydrogen of the acid by a positive 
element or grouping. 

EXAMPLE. 

H 2 C 4 H 4 6 = hydrogen tartrate — acid. 

H K C 4 H 4 6 = { Mrogen potassium tartrate ) _ id j 

4 * fa (or acid potassium tartrate J 

Acid salts usually turn blue litmus red, but this is by no means 
universal. In Exp. 39, if one-half as much sodium nitrate be taken, 
with strong sulphuric acid, an acid salt, instead of a normal salt, results. 

Na N0 3 + H 2 S 4 = HNaS0 4 + HN 3 

acid 
sodium 
sulphate 






APPENDIX. 141 

In general, by adding an excess of the acid (which is the same as 
taking less of the other substance), an acid salt maybe obtained. Acid 
salts, as a rule, react with carbonates like acids, that is, forming a salt 
(normal), water', and cai'bon dioxide, as: — 

s 

2HKC.HA + K 2 C0 3 = 2K,C 4 H 4 6 + H 2 + C 2 

acid salt carbonate normal water carbon 

salt dioxide 

A double salt is one which is formed by replacing part 
or all of the replaceable hydrogen of the acid by two pos- 
itive elements or groupings. 

EXAMPLE. 

IL^C^H^Oq = tartaric acid. 

K Na C 4 H 4 6 — potassium sodium tartrate == double salt. 
("Rochelle salt") 

H 3 P 4 = phosphoric acid. 

H Na H 4 N P 4 = hydrogen sodium ammonium phosphate = 
double salt (microcosmic salt). A double salt may be at the same time 
an acid salt, like the last. 

A double salt may be formed by an acid salt of one metal acting on 
the carbonate of the other, thus: — 

Na ? CO s + 2HKC 4 H 4 6 = 2 K Na C 4 H 4 G + H 2 + CO, 

water carbon 

dioxide 

Acids containing one, two, three, etc., atoms of replaceable hydrogen 
are said to be respectively monobasic, dibasic, tribasic, etc. 

H JS" 3 = monobasic acid. 

H 2 S 4 = dibasic acid. 

H 3 P 4 — tribasic acid. 

H 4 Si 4 = tetrabasic acid. 

Note. — A tribasic acid may form two acid salts, as: — 

H 2 Na P 4 = dihydrogen sodium phosphate = acid salt. 

H Na 2 P 4 = hydrogen disodium phosphate = acid salt. 

A basic salt is one which may be formed by replacing 
one or more hydrate groupings of the base by a negative 
grouping. [This definition is a narrow one, covering most 



sodium 


acid 


double 


carbonate 


potassium 
tartrate 


salt 



U2 CHEMICAL PRIMER, 

but not all basic salts. It may be, however, that basic 
sajts are molecular compounds of the hydrate (or oxide) of 
the metal with the metallic salt, the hydrate uniting after 
the analogy of water of crystallization.] 

EXAMPLE. 

Pb 2 H = lead hydrate = base. 

Pb HONO3 = lead hydro-nitrate = basic salt. 

Al 2 GHO - aluminum hydrate = base. 

ALj (H 0) 2 Si Oj = aluminum hydro-silicate = basic salt. 

Bi 3 H = bismuth hydrate = base. 

"R- ^tt n\ Ain f basic bismuth nitrate, "subnitrate of bismuth," 

J5i (±1 U) 2 JN U 3 — J uged largely in mec ii c i ne . 

Sulph- and selen-acids and salts. In all formulas for 
ternaries thus far explained, oxygen has been the last ele- 
ment. It is supposed to be principally a linking or connect- 
ing element. Now there are a few other dyad elements 
that can perform this office of linking, especially sulphur 
and selenium. To write the formula for a sulph- or a 
selen-acid or salt, the same reference table may be used, 
only sulphur or selenium, as the case may be, must be 
substituted atom for atom, in place of oxygen. 

EXAMPLE. 

K 2 C 3 = potassium carbonate = salt. 

K 2 C S 3 = potassium sulpho-carbonate — sulph-salt. 

Ag 3 As 0^ = silver arsenate = salt. 

Ag 3 As S 4 = silver sulph-arsenate = sulph-salt. 

K 3 Sb 3 = potassium antimonite = salt. 

K, Sb Se 3 = potassium selen-antimonite = selen-salt. 

H 3 As S 4 = hydrogen sulph-arsenate ~ sulph-acid. 

Note. — Instead of sulph-, thio- (Greek thlon, sulphur) is used by some 
chemists, as K 2 C S 3 = potassium thio-carbonate. 

The sulph- and selen-acids and salts are few compared to those con- 
taining oxygen. 



APPENDIX. 143 



SECTION B. 



THE ALLOY, SPECTRUM ANALYSIS, AND 
SYSTEMS OF CRYSTALLIZATION. 

The most important alloys (with their usual proportions) are: — 

Aluminum Bronze Cu (9) Al (1) 

Bell-metal Cu (9) Sn (2) 

Brass Cu (2) Zn (1) 

Bronze Cu (95) Sn (4) Zn (1) 

Coin (gold) Au (90) Cu (9) Ag (1) 

Coin (silver) Ag (9) Cu (1) 

Fusible Metal Bi (see) Pb Sn 

German Silver Cu (5) Zn (2) M (2) 

v — brass — *. 

Hard Solder Cu (1) Zn (1) 

Pewter Sn (4) Pb (1) 

Phosphor-bronze Cu (38) Sn (10) P (1.5) Pb (.5) 

Shot../ Pb (99.5) As (.5) 

Soft Solder Pb (1) Sn (1) 

Type-metal Pb (70) Sb (20) Sn (10) 



The spectroscope , next to the balance, is the most useful instrument 
for original chemical research. It consists of a prism, mounted upon 
a stand, carrying a tube with fine, adjustable slit, through which light 
(the rays being made parallel by a lens) falls upon the prism. The 
light, refracted by the prism, is received by a small telescope, which 
magnifies the spectrum ("rainbow," if solar spectrum, i. <?., if light is 
sunlight) before it reaches the eye. The spectrum of the sun has dark 
lines (Frauilhofer's lines), crossing it at right angles all along from 
the red to the violet portion, but at irregular intervals. The relative 
position of these lines has been accurately determined. 



144 



CHEMICAL PRIMER. 



If, instead of sunlight, the light from the sodium flame (Exp. 130) 
enters the slit, no colored bands from red to violet, as in the solar spec- 
trum, are seen. Instead, the spectrum is totally dark except a brilliant 
yellow line (double) crossing the spectrum where before (in solar spec- 
trum) was the dark line D (double). If the light of the potassium flame 
enter the slit, three lines appear on the dark spectrum: a bright pur- 
plish line at (what was before) the violet end, and at the other end two 
red lines— one somewhat bright, the other very faint. 



SPECTRA OF 









<D 
















R 


ed 




§ Yel 


low 


Gr 


ee 


n 


Bl 


ue 


Indigo Vio 


let 








o 



















ABC 



E b 



Sun with 

few dark lines 

shown. 



Sodium. 



Yellow line 



Red lines 



Potassium. 



Purplish line 




Strontium. 



All the other metals and non-metals have characteristic spectra, but 
some substances require more heat than the flame of the Bunsen's burner 
to volatilize them. For these the electric flame is used. With a small 
spectroscope, however, the student can easily obtain the spectra of Na, 
K, Ba, Sr, and Ca, whose chlorides are volatilized in Bunsen's or alcohol 
flame. [See Fig. 43. For some laboratory spectroscopes, spectra are 
reversed and Fig. 43 must be turned upside down to represent the view.] 



APPENDIX. 145 



Many rare metals have been discovered by means of the spectroscope 
(caesium, rubidium, thallium, indium, etc.). By it the light of the heav- 
enly bodies reveals the presence in these orbs of many elements com- 
mon upon the earth. (Celestial Chemistry.) 



Most chemical substances, when they pass from the liquid to the solid 
state, assume some definite form and are said to crystallize, (See 
Exp. 34 and connection.) It has been found possible to arrange all 
crystals in six systems, according to the arrangement of their sides and 
angles around certain imaginary axes, intersecting at the center of the 
crystals. These axes are shown on_y in Plates I and n of Fig. 44. 

1. Regular System, — Three axes all equal and all at rigid angles. 
Plates I, ii, and in. Ex. : Common salt, alum, garnet. 

2. Hexagonal System. — Four axes, three equal and in one plane, 
making angles of 60°, and one, longer or shorter, at right angles to the 
plane of the other three. Plates iv and v. Ex. : Sodium nitrate, 
quartz, and ice. 

3. Quadratic System, — Three axes all at right angles, and one 
shorter or longer than the other two. Plates vi and vn. Ex. : Potas- 
sium ferrocyanide and tin dioxide. 

4. Rhombic System.— Three axes all unequal and all at right 
angles. Plates viii and ix. Ex. : Potassium nitrate, barium sulphate, 
and sulphur, crystallized from solution in carbon ljisulplo.de. 

5. Mouoclinic System. — Three axes all unequal. Two cut each 
other obliquely, and one is at right angles to the plane of the other two. 
Plate x. Ex. : Sodium carbonate, sodium phosphate, ferrous sulphate, 
borax, cane-sugar, and sulphur from fusion. 

6. Triclinic System.— Three axes, all unequal and all oblique. 
Plates xi and xn. Ex. : Copper sulphate, manganese sulphate, boracic 
acid and potassium bichromate. 

Certain substances, like S, crystallize in two systems, and are said 
to be dimorphous. A very few substances are trimorphous. Anything 
without crystalline form is amorphous (as plastic sulphur). Different 
substances that crystallize in the same form are isomo?phous (as com- 
pounds of the halogens with the same metal). A crystalline body splits 
more readily in a certain direction than others. This splitting is called 
cleavage. The powder of a crushed or scratched mineral is called its 
streak. 1Q 



146 



CHEMICAL PRIMER. 




Fig. 44. 



APPENDIX. 147 



SECTION C. 



DYEING. 



Exp. 1. — Dissolve a little aniline blue (C 20 H 16 (C 6 H 5 ) 3 N 3 ) in alcohol, 
and clip clean, white silk thread into it. Expose the thread to the air, 
the alcohol evaporates and leaves the blue color adherent to every fiber 
of the silk. 

Aniline (C 6 H 5 H 2 N) is a volatile, oily liquid; colorless, when pure, 
but by oxidation, action of chemical agents, etc., aniline^ black, red (ma- 
genta), orange, yellow, green, blue, and violet (mauve) are produced. 
The reactions in the formation of the wonderful "aniline dyes" are by 
far too complex for introduction here. 

Exp. 2. — Upon fine zinc filings in a beaker place a minute quantity 
of blue indigo, add a moderately strong solution of potassium hydrate 
(potash) and heat. 

(a)— Zn + 2KH0 = K Zn 2 + H 2 

nascent ' . _ 

(b)-H. 2 + C 16 H lt N 2 0, = C 16 H 12 NA 

reducing blue indigo white indigo 

agent 

Dip a piece of clean, white w^oolen (or cotton) cloth in the solution of 
white indigo and expose to the air, blue indigo is formed in its fibers by 
oxidation and adheres, that is, is a "fast" color (does not wash out in 
warm soap-suds). 

C 16 H 12 NA + = C 16 H W NA + H 2 

white indigo blue indigo evaporates 

Exp. 3. — Divide a dilute (1 per cent.) solution of picric acid 
(C 6 H 3 N\jO 10 ) into two portions. Into one dip a piece of woolen yarn, 
into. the other dip cotton yarn. Remove each and wash. The first is 
dyed a brilliant yellow, the second is not colored. 



148 CHEMICAL PRIMER. 

Substances that dye directly are called substantive colors. Coloring 
substances may form colored compounds with the fibers of the cloth, or 
(usually) may merely adhere to the fibers. Cotton and linen often 
require different treatment from wool or silk to produce the same color, 
and, in general, are dyed with more difficulty. 

Exp. 4. — Divide a solution of alum into two parts. To the first add 
H 4 N HO, a flocculent precipitate of aluminum hydrate (Al 2 6 HO) 
falls. To the second add a few drops of solution of cochineal {carmine 
ink), and then H^N H 0. Al 2 6 H O is precipitated as before, and 
slowly settles, carrying the coloring matter down with it, forming a 

"lake." 

Some other metallic hydrates (or oxides), especially of tin and of iron, 
have the same great affinity for organic coloring matter. The com- 
pounds they form with coloring matters are called lakes. The hydrates 
also have ' 'great affinity for" (adherence to) the fibers of cloth. Every 
one knows that, though "dirt" can be readily washed from a white 
apron, iron rust is removed with great difficulty (only by chemical 
agents — see Chemistry of Cleaning). Hydrates (or salts, from which 
the hydrates may be produced) that have a great affinity for coloring 
matter and also for the fiber of cloth, are called mordants, and a color 
that will not dye directly, but needs a mordant, is called an adjective 
color. 

Coloring by means of mordants is the usual method. The most 
common mordants are copperas, tin salts, and alum. The cloth is first 
dipped into a solution of the mordant and then into the dye. Of course 
different mordants produce different colors, when used with the same 
dye. The mordants may be applied by means of stamps (or rollers) and 
any pattern (as for calico) brought out in the various colors. 

Exp. 5. — Boil a piece of Ee S 4 in nitric acid (90 per cent.), till 
red fumes cease to appear; dilute and filter. Preserve filtrate (Fe 2 3 S 4 , 
"persulphate of iron"). Dip clean silk into this ferric sulphate (mor- 
dant) and leave for a few minutes. Drain, and immerse in solution of 
potassium ferrocyanide (dye). It is colored a deep blue (Prussian 
blue). 
2Fe 2 3S0 4 + 3K,Fe(CN) 6 = 6K 2 S0 4 + (Fe 2 ) 2 3 Fe (C N) 6 

mordant dye ferric ferrocyanide 

Prussian blue 

The reactions of the organic dyes with their mordants are too complex 
to be written out. Indeed, many of them are unknown. The most 
common coloring substances are madder (coloring principle alizarin, now 
made artificially from coal-tar), cochineal (dried insects from cactus of 
Central America, coloring principle, carmine), logwood, indigo, litmus, 
etc. (See Dyeing, in cyclopaedia.) 



APPENDIX. 149 



SECTION D. 



ADDITIONAL EXPERIMENTS. 

HYDROGEN AND OXYGEN. 

Exp. 1. — Repeat Exp. 30 with a test-tube of the right size and the H 
flame "sings." It sets the column of air in vibration within the test- 
tube. 

Exp. 2. — Ignite a small jet of H by holding in it platinum sponge 
(previously heated to expel absorbed gases which hinder the action). 

Exp. 3. — Place a sounding tuning-fork in a jar of H; the tone is raised 
to a shrill pitch. 

Exp. 4. — Burn a minute jet of [driven by reservoir (1) from holder 
(3) as in frontispiece] in a jar of H, quickly igniting the jet by passing 
through burning H at the mouth. (See Xote Exp. 26. ) [Bore hole in 
receiver (1) with rat-tail file moistened frequently by turpentine.] 

Exp. 5. —Connect H and holders with oxy-hydrogen blowpipe 
(Fig. 17), and igniting the H first, turn on the 0. l^laee small piece of 
fine Pt wire (fused into glass holder, Fig. 40) in the flame. It melts. 
[The rubber cork in the H holder should be well oiled and firmly bound 
down by strong twine fastened to shoulder of the bottle. The H should 
be drawn into a test-tube over water and tested before it is burned in 
the blowpipe. If it burns quietly after taking fire it is safe to ignite 
jet. If it burns explosively, it is mixed with air and must not be ignited. 
The holder is first filled completely with water and the H (from genera- 
tor as Frontispiece 2) or pressing backward expels the water, the 
reservoir being kept so that the water in it shall be only about a deci- 
meter above the water in the holder. Common illuminating gas may be 
used instead of hydrogen with practically the same results.] 



150 



CHEMICAL PRIMER. 



Exp. G.— Into a tube closed at one end (through which Pt wires are 
fused with the internal ends almost but not quite touching) filled and 
inverted over mercury, put 2 cu. cm. of O and 4 cu. cm. of H and ex- 
plode by electric current. The mercury rises and with the water above 
completely fills the tube (except perhaps a bubble of gas, which is the 
result of inaccurate measurement). Composition of water is proved by 
synthesis, as nothing is found dissolved in the water. 



CHLORINE. 



Exp. 7. — Mix in the dark, dry CI and dry H in a stout bottle, and 
with care explode by sudden exposing to direct sunshine. H CI fumes are 
formed. 

Exp. 8. — Fill jar with H CI gas and make hydrochloric acid fountain 
similar to ammonia fountain of Fig. 22. 



SULPHUR. 

Exp. 9. — Repeat Exp. 92 and afterward immerse rose in dilute sul- 
phuric acid. The color is restored to nearly the original tint. 

Exp. 10. — Place in a small flask (provided with safety tube as in Fig. 
25, or as in H 2 S generator in Frontispiece 2) pieces of copper wire (or 
"drop copper") and add as much strong H 2 S 0^ as will not quite cover 
the copper. Carefully heat until gas begins to be evolved and then 
regulate heat; else the liquid froths from too violent reaction. 

Cu + 2H 2 S0 4 = CuS0 4 + 2H 2 + S 2 

Pass through small con- 
denser and connect conden- 
ser with apparatus (S 2 
condenser) shown in Fig. 
45, which is immersed in a 
freezing mixture (ice and 
salt). S 2 is easily con- 
densed by ' 'cold" to a liquid. 
Fig. 45-S0 2 Condenser. Tum gtop . cocks and pre . 

serve. Wire stop-cocks (Fig. 46) on rubber connectors (boiled in paraf- 
fine) may be used in place of glass stop-cocks. 




APPENDIX. 



151 



S 2 may also be condensed in strong glass tube (drawn to a point at 
Due end) by pressure of a plunger with close-fitting, greased rubber 
head. When pressure (at 15°) reaches one and one-half atmospheres, 
drops appear on the side, and liquid S 2 gathers in the lower part of 

the tube. If plunger is quickly 
withdrawn a part is frozen (by 
cold produced by sudden evap- 
oration) into a snow-white solid. 

Place water in a small plati- 
num or other thin -walled dish 
and pour around it a little 
liquid S 2 . Blow with bel- 
lows to hasten evaporation of 
S 2 . The r„,pid vaporization 
produces a cold ( — 50°) so great 
Fig-. 46-Spring Stop-Cock. (absorbs so much heat) that the 

water is quickly frozen. Mercury may be frozen if used instead of 
water. (It must not be put in platinum dish — why?) If S 2 be evap- 
orated in the receiver of an air-pump, a part will be solidified (frozen) 
forming snow-like solid. 




PHOSPHORUS. 

Exp. 11.— In a flask place ,a few minute pieces of P and cover with 
strong solution of caustic potash. Displace the air imthe flask by pass- 
ing H through the stopple of flask until the bubbles caught over pneu- 
matic tube of water burn quietly. Close by wire spring (Fig. 46) the 
rubber tube through which H is admitted and heat flask. 

y 

3KHO + P, + 3H 2 = 3KH 2 P0 2 + H 3 P 

The hydrogen phosphide (phosphine) takes fire because vapor of liquid 
P 2 H 4 is present and the beautiful white rings of smoke ascend. (Pure 
H 3 P is not spontaneously inflammable. ) Remove heat and pass H as 
before and throw away poisonous liquid. 



Caution. — Perform in a well ventilated room and immediately open 
doors and windows after the experiment. 



152 



CHEMICAL PRIMER, 



Exp. 12.— The best test for 
the element phosphorus (paste, 
rat poison) is that of distilla- 
tion. Place suspected sub- 
stance in flask, add dilute sul- 
phuric acid and pass vapor 
through a glass condenser (set 
in a perfectly dark box painted 
with black pigment on the in- 
side) and into water (Fig. 47). 
Look into the box by means of 
a small tube, while the head, 
like the photographer's in ad- 
justing his camera, is covered 
by dark cloth or shawl. The 
vapor is dl&tmctYy phosphorescent 
if even a minute quantity of free 
P is present in substance. The 
test determines with absolute 
certainty whether free phos- 
phorus is present. In cases of poisoning this test must be applied 
without long exposure to the air, as P in presence of organic matter and 
air rapidly oxidizes. 




Fig. 47. A— from flask. B— condenser. C D — 
cold water, a b c d— rubber tubes to ex- 
clude light. 



ARSENICUM AND ANTIMONY. 

Exp. 13. — Place a small piece of clean copper wire in arsenical solu- 
tion acidulated with hydrochloric acid, and boil. (H N 3 must not be 
present. ) Arsenicum is deposited on the copper. Wash, carefully dry 
and heat slowly in closed glass tube; octahedral crystals of As 2 3 are 
deposited. (Reiliscll's test.) 

Exp. 14. — Generate hydrogen by heating to near the boiling point a 
strong solution of Na H and Zn. 

y 

Zn + 2 Na H = Na 2 Zn 2 + H 2 

Add a few drops of a solution of "arsenic, 5 ' and pass gas through 
wash-bottle of lead acetate solution to remove accidental traces of 
H 2 S; spread over mouth of wash-bottle filter paper moistened with 
Ag N 3 . 

H 3 + As = H 3 As 
H 3 As + 3H z O + 6AgNO d = H 3 As 3 + 6 H N 3 + Ag 6 



APPENDIX. 153 



The free silver turns the paper purplish-black. (Fleitmann's test dis- 
tinguishes Arsenicum in presence of antimony. ) 



«=>#«= 



GOLD. 

Exp. 15. — To a solution of an auric salt (Au Cl 3 ) add H 2 S. A 
brown precipitate of Au 2 S 3 falls, soluble in (H 4 N) 2 S 2 . 

2AuCl 3 + 3H 2 S = Au 2 S 3 + 6 H CI 

Exp. 16. — To solution of salt of gold (Au Cl 3 ) add ferrous sulphate, 
and set aside for awhile. 

2AuCl 3 + 

Boil precipitate of free gold in H CI, mix with equal bulk of borax 
and fuse in strong blowpipe flame. A "button" of pure gold is obtained. 

Exp. 17. — Add a few drops of solution of stannous and stannic chlo- 
rides (CI water put into Sn Cl 2 gives Sn Cl 4 ) to dilute solution of Au Cl 3 , 
a purplish, finely-divided precipitate, "purple of Cassius" (composition 
doubtful), falls. The same precipitate is slowly obtained, if tin foil is 
placed in solution of Au Cl 3 . 



6FeS0 4 = 


= Au 2 


+ 


Fe, Cl 6 


+ 


2 Fe., 3 S 4 


ferrous 


free 




ferric 




ferrZc 


sulphate 


gold 




chloride 




sulphate 



SILVER. 

Exp. 18. — Sink a small piece of unsized paper into Na CI solu- 
tion for five minutes. Dry. In a dark box dip it beneath Ag N 3 
solution for one minute. Lay this "prepared paper" upon a flattened 
leaf which lies upon glass. Cover with an old book cover and expose 
the glass to sunlight. A white "picture" of the leaf is formed. Remove 
paper, and in dark box "fix" by dipping into sodium hyposulphite 
(Na 2 S 2 or hot Na CI solution) for five minutes. Wash by dipping 
alternately for three minutes at a time into sodium hyposulphite and 
then into clear water. If glass is used in place of paper to hold the 
Ag N" 3 and Na CI, a "negative" of the leaf is formed. 



MERCURY. 

Exp. 19. — In a solution of salt of Hg place a clean (by HN0 3 and 
afterward H 2 0) copper wire. It is soon coated with a mirror of Hg, 
more apparent if dried by blotting-paper and gently burnished with soft 



154 CHEMICAL PRIMER. 

cloth. An equivalent amount of copper passes into the solution to take 
the place of the displaced Hg. Cut off the mirrored end of the wire, 
and, placing in closed glass tube, heat. Hg distills and globules of the 
metal gather upon the sides of the tube. 

In almost any solution containing soluble compound .of Hg, it may be 
detected by this test. No test for Hg should be considered complete 
unless metallic globules are obtained. A lens will often reveal the 
globules, if the amount of mercury is exceedingly small. 

Exp. 20. — To mercmws nitrate add K I, green mercurows iodide 
(Hg 2 I 2 ) falls. To mercuric nitrate add K I, red mercun'c iodide (Hg I 2 ) 
falls (Exp. 10). Wash, dry, place in cold tube, and sublime. Hg I 2 
condenses on the sides of the tube in yellow crystals; rub crystals with 
stick, they change to the original red. This change of color may be re- 
peated indefinitely. 



COPPER. 

Exp. 21. — Into a solution of a copper salt (as Cu S 4 ) put a piece of 
clean iron. It is coated with copper, an equivalent amount of iron 
passing into solution. 

Cu S 0^ + Fe se= Fe S 0, + Cu (deposited on iron). 

Exp. 22. — Add H^ N H to cupric solution, a characteristic blue 

precipitate soluble in excess of H^N H is obtained. 

v 
Cu2N0 3 + 2HiNHO = 2 H, N N 3 + Cu 2 H 

precipitate 



ALUMINIUM. 

Exp. 23.— Thoroughly char on platinum foil, bread oontaining alum. 
Pulverize and boil in dilute H CI, filter, neutralize with ammonium 
hydrate; a fine precipitate of Al 2 6 H O (having very distinct surface as 
it settles) falls. Set aside; minute, distinct crystals appear. 



CALCIUM. 

Exp. 24. — Heat in oxy-hydrogen blowpipe flame the sharpened end 
of a stick of quicklime, a dazzling light is emitted ("lime light"). (Do 
not look steadily at the light. ) 



APPEXDIX. 



155 



BARIUM AND STRONTIUM. 




Fii r . -A 7.— Green Fire. 



Exp. "J."). — Pulverize sepa- 
rately with great care 
Ba 2 X 3 (oxidizing and col- 
oring agent 1 . K CI 3 (oxidiz- 
ing agent), and gum shellac 
(C and H principally, com- 
bustible body). Add one drop 
of strong H CI to the barium 
chlorate powder and mix care- 
fully and thoroughly equal 
bulk of each upon piece of 
paper. Place on wire gauze 
in shoal pan and ignite, using 
the paper as a fuse. It gives 
green fire. 



Exp 26.— Repeat Exp. 25, using Sr 2 X 3 instead of Ba 2 X 3 . 
Red fire results. 



ORGANIC CHEMISTRY. 

Exp. 27.— Repeat susrar test. 
Exp. 132. Albumen, if present, 
must be removed by boiling and 
filtering. Earthy phosphates 
should be removed by adding 
caustic potash to alkaline reac- 
tion and filtering. The caustic 
potash used must have been kept 
in the best Bohemian glass bottles, 
and not in bottles containing lead: 
otherwise Pb falls and is mis- Fig-. 49. 

taken for Cu 2 0. A mere yellow color is not suffi- 
cient, there must be an actual precipitate, without pro- 
longed boiling. — Perform the same experiment without heating, but set 
test-tube away for twelve hours instead. The Cu., is precipitated. 

Exp. 28. — Fill a test-tube entirely full of clear animal secretion con- 
taining sugar; add a small quantity of yeast and close the mouth of the 
test-tube by a rubber cork, through which runs a fine glass tube nearly 




Fiff. 48. 




156 CHEMICAL PRIMER. 

to the bottom of the test-tube (Fig. 48). Set in a warm place for ten or 
twelve hours. The C 2 , produced by the fermentation, collects in the 
top of the test-tube, and forces the liquid out of the fine glass tube. 
This Fermentation Test is an excellent one for sugar in animal secretions. 
Exp. 29. — Take the sp. gr. of a liquid containing sugar before fermen- 
tation and after; every "degree" lost corresponds to tlie presence of 21 
mgs. of sugar in 10 cu. cm. of the liquid ("1 grain of sugar per fluid 
ounce"). That is, if urinometer (Fig. 49) shows 1050 before and 1030 after 
fermentation, there are 420 mgs. of sugar in 10 cu. cm. of the liquid 
(or 20 grains per fluid ounce). This is Roberts'' quantitative test. 

Exp. 30. — Add a small quantity of albumen (Exp. 138) to distilled 
water, or to animal secretion filtered. Upon pure, colorless, nitric acid, 
in test-tube of small diameter, slightly inclined, allow the liquid to 
trickle from a pipette. A sharp, white zone appears at the junction of 
the two liquids, not dissipated by heat. This is an excellent test for 
albumen. (Urates, if present in excess, produce a somewhat similar 
white zone, but the zone is dissipated by heat much less than the boil- 
ing point. Be careful not to mistake the mere mixing of the zone by 
boiling, for dissipation. If liquid is highly colored, of course albumen 
will be tinged with the color.) 

Exp. 31. — Add to animal secretion containing albumen, a few drops 
of strong caustic potash, and filter. Add nitric acid to distinct acid 
reaction and boil. White coagula appear (greenish, if bile is present, 
brownish-red, if blood is present). A good test for albumen. (Rarely 
it is necessary to allow to cool, and then boil the second time.) 

Exp. 32. — Precipitate a large amount of albumen from solution (Exp. 
138) in distilled water, by adding nitric acid and boiling. Filter, wash, 
and dry over water-bath. Arrange a dozen narrow, deep test- 
tubes nearly filled with the acid water. Carefully weigh out, by means 
of a fine pair of scales (any chemist will allow the use of his scales), 5, 
10, 15. . . .55, 60 mgs. of albumen powder, and placing in each test- 
tube respectively, allow about three times as long for settling 
because of dryness of albumen. By means of a very fine, sharp 
file, carefully mark the height of the precipitated albumen. Reserve 
test-tubes for quantitative testing for albumen. For example : If 5 cu. 
cm. of liquid to be tested were placed in first test-tube, and the precip- 
itated albumen reaches to the mark on the test-tube, 1 mg. of albumen 
is present in every cu. cm. of the liquid. This is a very convenient 
approximate quantitative test for albumen. 



APPENDIX, 157 

TESTS FOR THE ALKALOIDS. 

Exp. 33. — Upon small piece of a salt of morphia on glass slide, place 
a drop of water. Warm till salt is dissolved. Place beside it a minute 
drop of strong neutral solution of perchloride of iron (Fe. 2 Cl 6 ). Bring 
together by glass rod, a dirty-blue color results. 

Exp. 34. — To solution of a salt of morphia, add sodium carbonate 
solution A white precipitate falls, crystalline if solution is dilute. 
Test as in Exp. 33 above. 

Exp. 35. — Moisten a salt of morphia with nitric acid; an orange-red 
color results. 

Exp. 36.— To a few drops of an aqueous solution of opium, add drop 
by drop neutral solution of perchloride of iron. A red solution of mec- 
onate of iron is formed, not destroyed by addition of corrosive sublimate 
solution. 

Exp. 37. — Heat morphia on platinum foil, it burns and leaves no res- 
idue. 



Exp. 38. — To solution of quinine (or of its salts) slightly acidulated 
with H CI, add fresh chlorine water, and then ammonia water; a green 
coloration is produced. 

Exp. 39. — Repeat Exp. 38, but add potassium ferrocyanide before 
adding ammonia; an evanescent red coloration appears. 

Exp. 40. — Upon quinine (or its salts) let fall a few drops of strong 
sulphuric acid. It dissolves, producing faint yellow color. 

Exp. 41. — Repeat Exp. 40, with quinine that has been adulterated 
with the cheaper salicin, a deep red color appears. 

Exp. 42. — Dissolve quinine in cold nitric acid; a colorless solution is 
formed. Heat, it turns yellowish. 

Exp. 43.— Heat quinine on platinum foil, no residue is left. 



Exp. 44. — Place a small particle of strychnia on a white dish and 
near it a small piece of potassium bichromate. Add a drop of strong 
sulphuric acid to each and after a few moments bring the bichromate 
upon the strychnine drop with a glass rod; a vivid purple color ap- 
pears, rapidly fading into yellowish red. 



158 CHEMICAL PRIMER. 

Exp. 45. — Upon a drop of dilute solution of strychnia on glass slide, 
place drop of potassium sulphocyanide; a white precipitate appears. 
Examine with microscope and tufts of auricular crystals are seen. 

Exp. 46. — Add strong sulphuric acid to a crystal of strychnia and 
heat over water-Jxith; it is unaffected. 

Exp. 47. — Add strong, cold nitric acid to a crystal of strychnia; it is 
unaffected. Heat, it turns yellow but does not dissolve. 

Exp. 48. — Place a small frog in water containing traces of strychnia 
and in two or three hours (sooner if stronger solution is used) a slight 
jar throws him into the characteristic tetanic spasms. 



Exp. 49. — Place a drop of tincture of aconite upon the skin, a tin- 
gling sensation is produced followed by prolonged numbness. 



Exp. 50. — To a solution of atropia (belladonna) add a few drops of 
perchloride of gold; a yellow precipitate appears. — One drop of very 
dilute aqueous solution, applied directly to interior of eyelid, powerfully 
dilates the pupil. 

-# $ -H* 

NOTES. 

(1) Uncrystallizable substances (colloids) in solution diffuse slowly 
through a septum, as parchment paper; while crystallizable substances 
(crystalloids) diffuse rapidly. If a small hoop, covered with parchment 
paper and filled with mixed solution, be floated upon water the crys- 
talloids pass rapidly through while the colloids principally remain be- 
hind. This process of separation is called Dialysis. The so-called 
"dialyzed iron" is the colloid, the basic oxy-chloride of iron. (2) See 
larger works as to properties of C 2) as to condensation of H; and late 
scientific journals as to whether shellac may not be principally an ani- 
mal product. (3) The soap bubble experiment, page 51, sometimes 
fails because too strong acid is used, and acid moisture being carried 
over in the draft makes the bubble brittle. But inquiries as to "what's 
the matter?" is a fruitful source of chemical knowledge. 



QUANTITATIVE TEST FOR CARBON DIOXIDE IN SCHOOLROOMS (AS AN INDEX TO THE 
AMOUNT OP POISONOUS "ANIMAL VAPOR" PRESENT). 

The proportion of carbon dioxide is generally estimated by volume and on a scale of 
so many parts in 10,000 of air. In pure out-door air there are about 4 parts of carbon 
dioxide in 10,000 of air. In the school-room the proportion should never rise above 8 
parts. Examination of the following reactions and explanations will reveal the sim- 
plicity of the test. 

Ba2HO + H 2 C 2 4 , 2H 2 = BaC 2 0, + 4H 2 

barium crystallized barium water 

hydrate oxalic acid oxalate 

171 126 

Ba2HO + C0 2 = BaC0 3 + H 2 

171 44 

In neutralizing power. 

126 gms. of cr. oxalic acid = 171 gms. of barium hydrate. 
44gms. ofC0 2 = 171 " 

therefore 44 gms. of C 2 = 126 " of cr. oxalic acid. 
1 gm. C 2 = 2.863 + gms., or 2863 mgs. of cr. ox. acid. 

If we weigh carefully 2863 mgs. of cr. oxalic acid (not deliquesced) and dissolve in 
1,000 cu. cm. (litre) of distilled water, then 1 cu. cm. of that "standard" solution will 
equal (in neutralizing power) 1 milligram of carbon dioxide. (.Keep solution in dark 
bottle. Prepare new solution of acM every two or three weeks. The most important 
thing in the test is that the oxalic acid solution be fresh and made from perfect crys- 
tals.] 

We then make a solution of barium hydrate dissolving about 5 gms. in a litre of 
water. 

Suppose a jug (bottle) with tight-fitting rubber cork holds 4,155 cu. cm. (carefully 
measured), which jug we fill from the air of the schoolroom by means of a small bel- 
lows (blown a sufficient number of times, say 25), and take temperature of the room 
at the same time as 20°. Into this we pour from a sp. gr. bottle (holding with the 
$lass stopper in, 100 cu. cm.) 100 cu. cm. of the barium hydrate solution and shake 
thoroughly at intervals. We now fill the burette (Frontispiece 5) with the "standard" 
solution of oxalic acid, to a point a little above and run it down carefully drop by 
drop to the point precisely. Measuring from barium hydrate solution (by means of 
another sp. gr. bottle holding 50 cu. cm.) 50 cu. cm. we pour it into a clean, wide- 
mouthed bottle, rinse with distilled water and pour this in also. We now add a little 
blue litmus solution (or brown solution of turmeric). Open the burette and allow the 
acid to run slowly (the last drop by drop) into the wide-mouthed bottle containing the 
50 cu. cm. of barium hydrate solution. It takes say 24.5 cu. cm. of acid to neutralize 
the alkali — when the last drop needed is added the litmus suddenly turns red (tur- 
meric turns yellow). Now carefully fill the second sp. gr. bottle (holding 50 cu* cm.) 
with the solution taken from the jug containing .the schoolroom air. Again fill the 
burette as before and see how many cu. cm. of the acid are required to neutralize the 
50 cu. cm. taken from the jug. We find in every case it requires less, because the 
carbon dioxide in the jug has already neutralized part of it. It requires, say, 22 cu. 
cm. of the acid. 24.5 cu. cm. — 22 cu. cm. = 2.5 cu. cm. But from equations above 
we know that 1 cu. cm. of the acid corresponds to 1 mg. of carbon dioxide; therefore 
as we poured out only one-half of the alkali to test there were 5 mgs. of carbon dioxide 
in the jug. From table we see that 1 mg. of carbon dioxide at 20° occupies .544470 cu. 
cm. of space, therefore 5 mgs. occupy 2. 72235 cu. cm. The question then becomes, — 
If in 4055 (4155-100) cu. cm. of air there are 2.72235 cu. cm. of carbon dioxide, how 
much carbon dioxide in 10,000 cu. cm. of air ? We have the proportion 

4,055: 10,000:: 3.72235: 
from which we obtain 6.7 parts in 10,000 as the answer, that is, the room is fairly 
ventilated. 

Space occupied by 1 mg. of C 2 at different temperatures (barom. 760 mm.). 



Degree 


Desree 


Cubic Cm. 


Degree 


Degree 


Cubic Cm. 


Degree 


Degree 


Cubic Cm. 


c 


F 




c 


F 




c 


F 







32 


.507306 


21 


69.8 


.546328 


28 


82.4 


.559336 


15 


59 


.535178 


22 


71.6 


.548186 


29 


84.2 


.561194 


16 


60.8 


.537037 


23 


73.4 


.550044 


30 


86. 


.563052 


17 


62 6 


.538895 


24 


75.2 


.551903 


31 


87.8 


.564910 


18 


64.4 


.540753 


25 


77. 


.553761 


32 


89.6 


.566769 


19 


66.2 


.542611 


2o 


78.8 


.555619 


33 


91.4 


.568627 


20 


68 


.544470 


27 


80.6 


.557477 


34 
35 


93.2 
95. 


.570485 
.572343 



A factor can be worked out for each jug used and for each temperature, so that by 
a simple multiplication of the difference shown by the burette the result is obtained. 
[The factor of this jug for this temperature is 2.68+. Dif. by burette 2.5 x 2.68+ = 
6.7+.] Any bright pupil can master the test in a few hours and can apply it in a few 
minutes by using factors. The test can be made after school or before school the next 
day. Such tests regularly reported would do much to awaken an interest in having 
a proper system of ventilation. 



160 



CHEMICAL PRIMER. 



SECTION E. 



METRIC SYSTEM. 



Linear. 



10 Millimetres (mm.) = 1 Centimetre (cm.) 
10 Centimetres = 1 Decimetre (dcm.) 

10 Decimetres — 1 Metre (m) 

10 Metres = 1 Dekametre 

10 Dekametres = 1 Hektometre 

10 Hektometres = 1 Kilometre 

Weights. 

10 Milligrams (nig.) = 1 Centigram (cgm.) 
10 Centigrams = 1 Decigram (dc/.) 

10 Decigrams = 1 Gram (gm.) 

10 Grams = 1 Dekagram 

10 Dekagrams = 1 Hektogram 

lOHektograms = i ( Kflg™n(kgm.) 

1,000 Kilograms = 1 Metric Ton (M. T.) 



Capacity. 



10 Millilitres 
10 Centilitres 
10 Decilitres 
10 Litres 
10 Dekalitres 
10 Hektolitres 



= 1 Centilitre 
= 1 Decilitre 
= 1 Ldtre 

= 1 Dekalitre 
= 1 Hektolitre 
= 1 Kilolitre 



1 Metre (meter) = 39.37 inches. 

1 Litre = 61 cubic inches. 

1 Litre = 1 cubic decimetre. 

1 Gram = 15.43 grains. 

1 Gram = weight of 1 cu. cm. of 

water 4 e ) 
1 Kilogram = 2 1-5 lbs. 
1 Kilogram = weight of 1 cu. dcm. (litre) 
of water (4°) 



lsq. 
cm. 



1 Decimetre = 10 Centimetres. 



REFERENCE TABLE No. 2— Continued. 
Negative Groupings. 
^P 3 = metaphosphate 
C 5 H 9 5 = valerianate 



x -I 



CNO = cyanate 

CH0 2 - formate 
I C 4 H 7 2 = butyrate (butter) 

C 7 H 5 2 = benzoate 
VN 2 == nitrite 

'C 4 H 3 5 = malate 

C 7 HOj = meconate (opium) 

C 7 H 3 5 = gallate 
, C 27 H 19 17 = tannate 

Fe 2 (C N) 12 = ferricyanide 






C 3 H 4 3 = lactate 
C 5 H 2 N 4 3 = urate 
B^ O r = tetraborate (borax) 
Mn 4 = manganate 
Mn 2 8 = permanganate 
Cr 2 7 = bichromate 



Fe (C N) 6 = ferrocyanide 



Positive Grouping. 
H 2 N = amidogen 



APPENDIX. 161 

SUGGESTIONS FOR STUDENTS USING THE ANALYTI- 
CAL CHARTS. 

In small schools this should be a volunteer class and the work extra, 
put in after school hours or on Saturdays. Be sure you want to do the 
work before you undertake it. Don't talk to others while at work, ex- 
cept in rare instances so far as quietly to obtain information. Don't 
"fool" in the laboratory and report those who insist upon doing it, that 
they may be promptly removed from the class. Have no false honor 
about this, for the nonsense of one may vitiate all accurate work for a 
class. — Reserve a portion of the original solution to begin upon again in 
case of accident, also for special tests. — Common drinking water, boiled, 
cooled, and filtered, usually answers for all work with the first two 
Groups; but distilled water must be used for the other Groups, and is 
better for all reagents. — Precipitate thoroughly each Group, but on the 
other hand avoid much excess of the precipitating reagent. — Evaporate 
filtrates if they become too dilute. A coal-oil stove makes a cheap 
source of heat for evaporation. — Avoid breathing, to any great extent, 
fumes of hot H CI, H^N HO, HN 3 , aqua regia, etc. Hold dishes at 
arms' length while pouring such liquids. Under a gas chimney with 
flame at base to increase draft, is the proper place to generate noxious 
fumes; but such work may be easily done upon a shelf by open window 
with slight outward draft. — Make (H 4 N) 2 S by passing H 2 S into dilute 
H 4 N H (10%) till saturated and then add ^qual volume of H 4 X H 0. 
Digest this with a little S and filter to make (H^N) 2 S 2 {yellow), or expose 
(H±N) 2 S to air for sufficient time. — A convenient H 2 S generator is 
shown in Frontispiece (2). The middle bulb contains Fe S. A test- 
tube with small hole in bottom (containing a little broken glass upon 
which is Fe S), lowered into wide-mouthed bottle of dilute H 2 S 4 and 
test-tube closed by perforated rubber stopple through which is glass 
tube connected with rubber tube held by spring, Fig. 46, makes a cheap 
H 2 S apparatus. — Fig. 50 shows a convenient reagent bottle with pipetted 
stopple. Take test-tube to bottle to add reagent, not bottle to test- 
tube, and be careful not to stir up any sediment which may have fallen 
in case drinking water has been used. — Fig. 51 represents a system of 
rapid filtration. The stream of water must be regulated. The longer 
the tube a, the more rapid the filtering. Chamber o must be air-tight 
at top. Pt (foil) funnel-shaped tip must support filter paper at bottom, 
and the wet edges of filter paper must be pressed firmly against upper 
part of funnel. A partial vacuum is formed in chamber b and flask c ; — 
For color of precipitates, additional tests, etc., see Exp. 97 and Index, 
also have a work on Qualitative Analysis upon the desk for reference. 



162 



CHEMICAL PRIMER. 



I. Add H CI (15 per cent.) drop by drop till upon settling no pre- 
cipitate falls Filter. 



Precipitate Hg 2 Cl 2 , Ag CI, Pb Cl 2 , insolu- 
ble chlorides. Wash twice with cold water 
(Fig. 7), drain, and washing from paper with 
wash-bottle into beaker, boil for one minute, 
and Filter while hot. 



Filtrate. . . soluble 
chlorides of other 
metals, Cu, Bi, Fe, 
Mg also traces of 



Precipitate Hg 2 Cl 2 , Ag CI. Wash 

with hot water to remove all of the Pb Cl 2 , 
if Pb has been found, drain, and add warm 
H 4 N H (15%), pouring it through two 
or three times. The ammonia water dis- 
solves Ag CI but reacts with Hg 2 Cl 2 . 



Precipitate 
H 2 NHg 2 Cl = amido- 
mercurous chloride black. 
(If no black color ap- 
pears no mercury in ous 
form is present.) Dis- 
solve in beaker a portion 
in five or six drops of 
aqua regia and evaporate 
carefully nearly to dry- 
ness, dilute and test so- 
lution of HgCl 2 (1) by 
Exp. 19, Appendix, or 
(2) by adding a drop of 
Sn Cl 2 and white Hg 2 Cl, 
is precipitated. Add excess of Sn Cl 2 and 
gray metallic Hg falls forming into globule 
if boiled with H CI. 



Filtrate... Ag CI 
AddHN0 3 (15%) 
to acid reaction. 
Ag CI is reprecip- 
itated because its 
solvent is neu- 
tralized. Filter, 
.... wash .... and 
fuse on charcoal 
as in Exp. 113, 
obtaining silver 
globule with no 
incrustation o n 
coal. 



Filtrate PbCl 2 

(Hot water dissolves Pb Cl 2 ) 

(1) Place drop of filtrate on 
glass and slowly evaporate 
white needle-shaped crystals 
of Pb Cl 2 are left, touch with 
drop of K I solution, yellow 
Pb I 2 appears. Divide fil- 
trate into three portions and 
to first portion 

(2) Add H 2 S 0, (15%), ivhite 
Pb S 4 falls. To second 
portion 

(3) Add K 2 Cr 2 7 (3%) yellow 
Pb Cr 0^ falls. To third and 
largest portion 

(4) Add (H,N) 2 S, black Pb S 
falls. Fuse with little K 2 C 3 
on charcoal in reducing (near) 
flame of the blowpipe. Lead 
globule is obtained with 
yellow incrustation on char- 
coal. Globule is malleable. 
(Bi and Sb are brittle.) 



II. Evaporate flltiate from first gToup to small bulk, add ten drops of strong H CI 
and evaporate carefully nearly to dryness. Dilute with hot H 2 and pass H 2 S gas 
through hot solution Filter. 

Precipitate insoluble sulphides of Hg (ic), Cu, Pb, Bi, I Filtrate soluble chlo- 

Sn, Sb, As (Au, Pt). Wash with hot water digest ten I rides of other metals, 

minutes in (H 4 N) 2 S2 (yellow) Filter | Co, Fe, Mn, Mg, etc. 



Precipitate... Hg, Cu, Pb, Bi (sulphides). 
Wash with hot water, add strong, boiling 
hot H N O3, pouring it on several times. 
Filter 



Filtrate. . .Sn, Sb, As (Au, Pt) sulphides. 
Add dilute H CI, sulphides are reprecipi- 

tated filter, drain well, boil in little 

strong HC1 Filter. 



Ppt Hg.l Filtrate Cu, Pb,Bi. 

Dissolve in Add five drops strong- H 2 S O4 
aqua regia and and boil down to small bulk, 
test as in First Pb gives white precipitate. 
Group. 1 Filter 



Precipitate Pb j Fi it r ate Bi, Cu. 

Add H4NHO Filter. 



Ppt.. Bi white. Fuse 
with K 2 C O3 on char- 
coal... brittle globule. 



Filtrate. .Cu, deep 
blue solution . . .test 
by Exp. 21, App. 



Precipitate . . .As, yel- 
low. Wash and confirm 
by digesting in (H^N^ 
C O3 and reprecipitat- 
mg in filtrate As 2 O3 
by H CI, otherwise S 
from decomposition of 
(H4N) 2 S 2 may be mis- 
taken for As. 



Filtrate.. Sn,Sb. 
Dilute with water 
and place a small 
piece of clean Zn, 
and of clean Pt 
wire in the solu- 
tion. Sb forms a 
distinct black 
stain upon Pt. 
Dissolve in hot dilute 



Wash Pt wire. 

H N O3, remove wire, evaporate to dry- 
ness, add few drops dilute H CI and pass H 2 S. Orange-yellow precipitate, turns gray- 
ish-black by Exp. 110.— After Zn has all dissolved, filter and add drop of Hg CI2, 
white precipitate of Hg 2 C1-; indicates Sn. — (Au and Pt, rarely occur in solution ) 



ANALYTICAL CHARTS. 



163 



III. To filtrate from second group add H 4 N H till alkaline (avoid 
excess), then add H 4 N CI and (HJf) 2 S and warm gently for five min- 
utes Filter. 



Precipitate, .sulphides of Ni, Co, Fe, Mn, Zn, hydrates 
of Cr and Al. Wash with very dilute (H±N) 2 S and then 
with water. Add dilute H CI breaking bottom of paper 
and washing through into beaker .... Filter 



Filtrate. . . 
soluble com- 
pounds of 



| metals of iv and v Group. 



Precipitate . . .Ni, Co 
(sulphides). Fuse a por- 
tion in borax bead— blue 
indicates Co. Violet 
when hot and brown 
when cold indicates Ni 
alone. If both are pres- 
ent Co overpowers Ni 
colors.— Dissolve the re- 
maining ppt. in few 
drops of aqua regia, evap- 
orate to dryness, dissolve 
in few drops of water, 
add a little CoCl 2 and 
evaporate on white pa- 
per. Green indicates Ni. 



Filtrate Fe, Mn, Cr, Zn, Al. Add few drops of H N O3 

evaporate carefully nearly to dryness, dilute slightly, add 
KHO till strongly alkaline, boil carefully 3 minutes. Filter. 



Ppt....Fe, Mn, Cr. Wash 
with hot water. Fuse a por 
tion on Pt foil with small 
quantity of K 2 C O3 and 
K N O3. Deep green indi- 
cates Mn.— Dissolve a second 
portion in dilute H CI and 
add K 4 Fe (C N)6 Prus- 
sian blue indicates iron. — 
Dissolve residue in hut ace- 
t c acid and add Pb2C 2 H 3 2 
Chrome yellow ppt. indi- 
cates Cr. 



Filtrate Al, Zn. Add 

(H 4 N) 2 S in slight excess. Filter. 



Ppt Zn 

s late-white. . 
Heat upon 
charcoal, add 
drop of Co CI 2 



Filtrate.. Al. 
Add H CI to acid 
reaction, boil, fil- 
ter, and add di- 
lute H 4 N H O to 



and h e a t, alkaline reac tion 
again. ..green a fine (fioculent 
coloration. | if large amt is 

present) precjpitate shows Al. 
Confirm as with Zn . . .blue mass. 



IV. Evaporate nitrate from Third Group to dryness, dissolve, add few drops of 
H CI, boil, filter, and to filtrate add H4N CI, H^N HO to alkaline reaction, ana then 
(H ±ShC Os. 



Precipitate . . .Ba, Si\ Ca. Dissolve carbonates in dilute Filtrate. . .soluo'e car- 
(20%) acetic acid, add K2Cr 2 7 Filter, bonates of Fifth Group. 



Ppt Ba Cr 4 , 

yellow. Moisten 
with H CI and apply Ppt Sr s 0i 
flame test Exp. 125. moiste D with 
H CI and apply flame test Exp. 126. 



Filtrate. . . Sr, Ca. Add (H 4 N) 2 C O3, filter. Dissolve precipi- 
tate in H CI, add dilute H 2 S 4 and set aside for an hour Filter. 



Filtrate Ca. Add H N H O to alkaline reac- 
tion and (H4N) 2 C 2 04. Moisten wnite ppt. with 
H CI and applyflame test. Dull revindicates Ca. 



V. To filtrate from Fourth Group concentrated by evaporation add H 4 N H O to 
alkaline reaction and then H Xa 2 I* Oi ... let stand for ten minutes (till cold). 

Precipitate . . 1 Fii tra te Na, K (and H 4 N> Concentrate by boiling. Apply 

tt" %i \? p l n* fi avie tes t- Yellow indicates Na, purpluh K. If both are present 

v.- If* f^ ^-^ the yellow obscures entirely the purplish color. Look through blue 
white shows Mg gi ass a t flame, the Na color is not seen and the K color appears red- 
dish-violet. Either metal may thus be detected in the presence of the other. 

Tests for H.^N compounds of course must be applied to the original solution. Heat 
a portion of this with Na H O. H 3 N is recognized by (1) odor, (2) turns moist litmus 
paper, suspended in mouth of (but not touching) test-tube, blue, and (3) by fumes with 
glass rod dipped in dilute H CI. 



Pt wire for flame tests must be clean, indeed, all utensils should be. — 
To digest is to warm without scalding. C. P. stands for chemically pure, 
and C. P. acids, etc., must be used in analytical work.— Groups iv and 
v are best tested with the spectroscope (which see). — Na 2 C 3 may be 
used for K 2 C 3 . 



164 



CHEMICAL PRIMER. 




50. — Reagent Bottle. 



Glass tube should be 
nearly closed at top by 
fusion. 




' Fig. 51. 

Tube b should be slightly drawn at bottom and arranged so as to throw its stream 
straight down the tube a. Chamber b need not be drawn out as in cut, but may be 
closed by rubber cork. 



CLOSED-TUBE ANALYSIS. 



FOR SOLIDS OR RESIDUE FROM EVAPORATION. 

Notes. — Use hard glass tubes about 5 cm. long, with inside diameter 
of about 3 or 4 mm. Close tube in blowpipe flame. It is often best 
to pulverize the substance, especially when chemicals, as lime, etc., are 
to be mixed with it. To introduce solid into closed tube, fold longi- 
tudinally a very narrow strip of paper, and, placing substance on one 
end of grooved paper, introduce into the inclined tube; and, raising 
tube to the perpendicular, remove paper. This avoids spilling the sub- 
stance upon the sides of the tube. 

Heat substance gradually in closed end of glass tube. 

1. Water is given off — 

(a) of crystallization, 

(b) from hydrate, 

(c) mechanically included. 
Test Water with Litmus. 

(a) Alkaline reaction indicates H 3 N from ammoniacal salts (best 
liberated by adding powdered quicklime) . 

(6) Acid reaction indicates volatile acids as H 2 S 4 , HN0 3 , H CI, 
HBr, etc. These acids are best liberated by adding 
HKS (X. 



CLOSED-TUBE ANALYSIS. 165 

2. Gas is evolved. 

(a) Oxygen (tested by fine glowing taper) indicates nitrates, 

chlorates, bromates, iodates, and some peroxides. 

(b) Sulphur dioxide (tested by odor and litmus paper) indicates 

sulphates or sulphites. Drop of Fe 2 Cl 6 + K 6 2 Fe Cy 6 -f S 2 
gives Prussian blue (page 148). 

(c) Hydrogen sulphide (odor) indicates sulphides containing 

water, — blackens paper wet with lead acetate. 

(d) Nitrogen tetroxide (reddish-brown and odor) indicates nitrates 

or nitrites. 

(e) Carbon dioxide (test by drop of limewater on glass) indi- 

cates carbonates [rarely oxalates; see (/)]. 
(/) Carbon mon- oxide (blue flame) indicates oxalates. 
(g) Cyanogen (odor and carmine flame) indicates compounds 

of CN. 
(h) Ammonia (odor and reaction) indicates ammoniacal salts (or 

organic compounds containing N which char). 

3. Sublimate. 

A. White. 

(a) Ammoniacal salts warmed with quicklime give ammonia. 
(6) Chlorides of mercury, yellowish when hot, white when 
cold. 

1. Sublimes without fusing -ous chloride. 

2. Fuses and sublimes -ic chloride. 

(c) Fuses to yellow liquid and sublimes Sb 2 3 . 

(d) Sublimes to octohedral crystals As 2 3 . 

B. Gray or black (so-called metallic mirror). 

(a) Arsenicum (garlic odor with closed tube cut open) 

indicates the element or some arsenides. 
(6) Mercury indicates amalgams or some compounds of Hg. 

C. Other colors. 

(a) Yellow indicates S or some sulphides, red on rubbing 

(Exp. 20, App.) Hgl 2 

(b) Black when hot, reddish-brown when cold, indicates 

sulphide of antimony (high temperature). 

(c) Reddish-brown hot, yellowish-red cold, indicates sul- 

phides of arsenicum or mixture of sulphides and 
arsenides. 

(d) Black when hot, red on rubbing cinnabar. 

4. Change of Color without Volatilization. 

(a) White to yellow, white on cooling, " glows " zinc oxide. 



166 CHEMICAL PRIMER. 

(b) White to yellowish- brown, dingy yellow on cooling tin 

oxide. 

(c) Yellow to brownish-red (fusible), yellow on cooling lead 

oxide. 

(d) White to reddish-yellow (fusible), pale yellow on cooling 

bismuth oxide. 

(e) Red to black, red when cold (Exp. 2) mercuric oxide. 

(/) Red to black, red when cold ferric oxide. 

5. Fusion indicates alkaline salts. 

6. Charring usually with u fumes " and empyreumatic odor indicates 

organic matter. 

7. Decrepitation indicates alkaline chlorides, galena, and many 

minerals. 



BLOWPIPE ANALYSIS. 

BRIEF DIRECTIONS. 

Hold the blowpipe in the "way " which is least tiresome, and blow 
with distended cheeks. Learn to breathe comfortably and maintain 
all the while the blast. Do not blow so violently as steadily. To 
produce best the reducing flame, hold the nozzle of the blowpipe 
against, but not in, the flame. To produce oxidizing flame, hold 
nozzle projecting into the flame about one-third of the distance across 
the flame, as in Fig. 29. Incrustations are best produced by oxidizing 
flame, globules by reducing flame. 

Heat on charcoal (willow). 

1. Fusibility indicates — 

(a) Alkaline salts. 

(b) Antimony, lead, bismuth, zinc, tin, silver, gold, copper. 

2. Decrepitation indicates haloid salts, some substances with in- 

cluded water and many minerals. 

3. Deflagration indicates nitrates, chlorates, (bromates, iodates), 

and some peroxides. 

4. Intumescence indicates some substances containing water, as 

borates, alum, etc. 

5. Odor indicates many substances : rotten horseradish, Se ; garlic, 

As, etc., as above and below. 

6. Flame color indicates : red, Sr ; yellowish- red, Ca ; green, Cu, Ba, 

H 3 B 3 , and H 3 P 4 ; bluish, As, Pb ; violet, K. 



HEAT IN BORAX BEAD. 



167 



Mix thoroughly with sodium carbonate, and heat on charcoal. 

1. No incrustation. (Do not mistake ashes for incrustation.) 

(a) Gold, silver, and copper give malleable globules. 

(b) Iron, nickel, and cobalt give gray infusible powder. 

2. Incrustation. 

(a) White (oxide), volatile in reducing flame, brittle globule 

Sb. 

(6) Orange yellow hot, lemon yellow cold, volatile, globule brittle 

Bi. 

(c) Lemon yellow hot, sulphur yellow cold, volatile, globule 

malleable Pb. (Brittle if containing much Sb.) 

(d) Yellowish hot, white cold, non- volatile, surrounding malleable 

globule Sn. 

(e) White with no globule, odor As. 

(/) Yellow hot, white cold, globule burns with intense greenish- 
white flame Zn (if small, oxidizes without burning) . 

(g) Steel gray, brown fumes from consumed globule, bluish flame, 

and odor as above Se. 

Note. — Many sulphides, chlorides, bromides, and iodides produce 
incrustations without decomposition. 



HEAT IN BORAX BEAD. 

Hold bead on platinum loop, as shown in Fig. 40. 



Oxidizing Flame. 


Reducing Flame. 


Indication. 


Hot. 


Cold. 


Hot. 


Cold. 




yellowish-red 


grass green 


green 


emerald green 


chromium oxide 


violet 


reddish-brown 


gray to 
colorless 


gray to 
colorless 


nickel oxide 


violet to black 


red violet 
to black 


colorless 


colorless 


manganese 
oxide 


blue 


blue 


blue 


blue 


cobalt oxide 


green 


bluish-green 


colorless 


brown to red 


copper oxide 


yellow to red 


colorless to 

yellow 


green 


bottle green 


iron oxide 



"With flux of microcosmic salt, Silica (Si0 2 ) gives in both flames, hot and cold, 
characteristic "silica skeleton." 



168 CHEMICAL PRIMER, 



FLAME COLORATION. 

Moisten with H CI, and heat in alcohol flame or flame from Bunsen's 
burner, as in Fig. 40. Colors as above on charcoal, but better observed, 
especially if the room be only moderately light, if colors be observed 
on dark background, and if volatilizing flame be partly covered by an 
opaque chimney. See page 163 for distinguishing K in presence of 
Na. If Ca and Sr are both present, Ca shows yellowish-</reen through 
green glass, and Sr faint yellow. Through blue glass Sr gives purple 
to rose, Ca faint greenish- gray. Ca salts are more volatile than Sr 
salts, and Sr salts than Ba salts, so that if the three are present and 
substance is held in lower part of flame the colors appear in succession, 
Ba being most persistent. — Nitric and nitrous acids (liberated by drop 
of H 2 S 4 ), being very volatile, give bronze green, " border" color when 
brought near without touching lower part of flame. Green quickly dis- 
appears. — Boric and phosphoric acids should be liberated by drop of 
H 2 S 4 . — Copper chloride gives blue, then green. — Except as above, 
almost all flame colors are better obtained by moistening with H CI. — 
Students should study flame colorations produced by known substances 
before beginning upon the unknown. 



CHARTS FOR ACIDS. 

Note. — In testing for "bases" (metals, see page 35) by the ana- 
lytical charts, the student has noticed that we do not at the same time 
search for the negative groupings with which they are combined. By 
"acids," in analytical sense, are meant negative groupings in acids, 
whether in acids proper or in salts formed from those acids. The 
same rule is observed with respect to " acids," viz., we do not at the 
same time search for " acids " and for the positive element or group- 
ing with which they are combined. 

DIVISION I. 

Inorganic acids do not char when heated. 

Group I. 
Acidulate with H CI and 
Add Ba Cl 2 . 

1. White ppt., Ba S 4 , insoluble in H CI, indicates H 2 S 4 (that is, 

sulphates ). 



CHARTS FOR ACIDS. 169 

2. Crystalline ppt., BaSiF 6 , indicates H 2 SiF 6 (fluo-silicates, rare 
acid). 
Confirm 

1. Sulphuric acid. 

Pb 2 N 3 gives white ppt., Pb S 4 , soluble in Na H 0. Boil 
ppt. in H CI, and cool. Pb Cl 2 crystallizes out. 

2. Hydrofluo- silicic acid. 

K CI gives gelatinous ppt. of K 2 Si F 6 . 

Group II. 

To neutral or slightly alkaline solution 
Add Ba Cl 2 (precipitates soluble in H CI). 
White. 

1. Ba H P 4 soluble in H N 3 indicates H 3 P 4 . 

2. Ba 2 B 2 (metaborate) soluble in acids H 3 B 3 . 

3. Ba C 2 4 soluble in H N O s H 2 C 2 4 . 

4. BaF 2 HF. 

5. Ba C 3 soluble in acids with effervescence H 2 C 3 (or 

solution C 2 ) . 

6. Ba 2 Si0 4 (decomposed on adding HC1, and gelatinous ppt. of 

H 4 Si 4 separates) H 4 Si 4 . 

7. Ba S 3 (dissolved in H CI and reprecipitated by CI water as 

BaS0 4 )......H 2 S0 3 . 

8. Ba S 2 3 (thio-sulphate) soluble in H CI with yellow ppt. of 

sulphur H 2 S 2 3 . 

9. Ba As 3 and (10) Ba As 4 soluble in H 4 N H 0. These acids 

are best found in the tests for metals, and below. 

11. Ba I 3 soluble in H N 3 H I 3 . 

Yellow. 

12. Ba Cr 4 insoluble in H C 2 H 3 2 H 2 Cr 4 . 

Confirm 

1. Phosphoric acid. 

Mg S 4 + H 4 N H + H 4 N CI gives white crystalline ppt. of 

H 4 N Mg P 4 , insoluble in H 4 N H 0, soluble in H CI, H N 3 , 

and H C 2 H 3 2 . 

Note. — Pyro-phosphoric acid (H 4 P 2 7 ) with AgN0 3 gives 

white ppt. of Ag 4 P 2 7 , soluble in H N 3 and H 4 N H 0. With 

albumen H 4 P 2 7 gives no ppt. — Metaphosphoric acid (H P 3 ) 

with Ag N 3 gives white gelatinous ppt. With albumen floccu- 

lent, white ppt. With Mg S 4 + H 4 N CI + H 4 N H O gives no ppt. 



170 CHEMICAL PRIMER. 

2. Boric acid. 

(a) Add drop of H 2 S 4 and few drops of alcohol. Ignite. 

Characteristic green flame (Exp. 100). 

(b) Add H CI to solution of borate. Turmeric paper dipped into 

it and gently warmed turns brown. Brown touched with 
NaHO turns greenish blue. *•■' 

3. Oxalic acid. 

Ca S 4 or very dilute Ca Cl 2 produces white ppt. , Ca C 2 4 , 
insoluble in acetic acid. Ignite. White residue, Ca C 3 , 
effervesces with acids. 

4. Hydrofluoric acid. 

Add few drops H 2 S0 4 to ppt., and heat. Characteristic oily 
appearance and resulting H F etches glass of test-tube. 

[If much Si 2 be present, Si F 4 results ; conducted into water 
gives flocculent ppt. (tufts) of silicic acid. H 2 Si F 6 is left in 
solution.] 

5. Carbonic acid. 

Conduct C 2 from effervescence against drop of limewater on 
clear glass. Ppt. Ca C 3 (Exp. 33). 

6. Silicic acid. 

* , Fuse with microcosmic salt (Fig. 40) in non-luminous flame. 
Si 2 floats on bead undissolved, " silica skeleton." 

7. Sulphurous acid. 

Add to mixture of Zn and H CI ; H 2 S escapes and blackens 
paper wet with Pb 2 C 2 H 3 2 . 

8. Thio-sulphurous (hyposulphurous) acid. 

H CI or H 2 S 4 produces no immediate ppt. , but on standing 
yellow S is precipitated and S 2 evolved. 

9. Arsenous acid. 

Exp. 108 gives yellow Ag 3 As 3 , soluble in H 4 N H O. 

10. Arsenic acid. 

Exp. 108 gives chocolate, Ag 3 As 4 , soluble in H 4 N H O. 

11. Iodic acid. 

Heat ppt. O is evolved ; sometimes violet vapors. 

12. Chromic acid. 

(a) H 2 S in presence of H CI reduces solution to Cr 2 Cl 6 , green, 

with ppt. of S. 
(6) Lead acetate produces yellow Pb Cr 4 , soluble in Na H O. 



CHARTS FOR ACIDS. 171 



Group III. 

Precipitated by Ag N0 3 and not by Ba Cl 2 . 
Add Ag N0 3 . 

1. White ppt., AgCl, dark violet on exposure to light, insoluble in 

H N 3 , soluble in H 4 N H H CI. 

2. Pale yellow ppt., AgBr, insoluble in dilute H N 3 , soluble in 

strong H 4 N HO H Br. 

3. Pale yellow ppt., insoluble in H N 3 , with difficulty in H 4 N H 

HI. 

4. White ppt. (as in 1.) H CI 0. 

5. White ppt., Ag N 2 , soluble in large excess of water H N 2 . 

6. White ppt., Ag C N (soluble as in 3.) H C N. 

7. Black ppt., Ag 2 S, insoluble in dilute acids H 2 S. 

Confirm 

1. Hydrochloric acid. 

Heat residue from evaporation with H 2 S 4 and Mn 2 . CI is 
evolved (Exp. 65); greenish-yellow; odor, and bleaches litmus. 

2. Hydrobromic acid. 

(a) Bromides are decomposed by CI water, forming yellow 
solution (Exp. 81). Shake with ether, Br dissolves and 
yellow solution rises, leaving colorless liquid below. 

(6) Residue from evaporation heated with H 2 S0 4 , and Mn 2 
gives dark red vapors of Br. 

3. Hydroiodic acid. 

(a) Starch and CI water give blue by Exp. 85. [Excess of CI 

gives I Cl 3 , and blue disappears.] 
(6) Residue from evaporation heated with H 2 S 4 and Mn 2 

give violet vapors of I. 

4. Hypochlorous acid. 

Add dilute H CI to ppt. ; CI is evolved. 

5. Nitrous acid. 

Fe S 4 produces black solution of N in the Fe S 4 . 

6. Hydrocyanic acid. 

(a) Add Fe S 4 + Fe 2 Cl 6 . Make alkaline with K H 0, and 

heat gently for five minutes. Acidify with H CI. Ppt. 
of Prussian blue. 

(b) Add H CI to ppt. or to residue from evaporation ; HCN 

with characteristic odor is evolved. Bring gas against drop 
of (H 4 N) 2 S 2 (yellow) on glass; H 4 N C N S is formed. 
Touch with Fe 2 CL -f H CI ; blood-red color results. 



172 CHEMICAL PRIMER. 

7. Sulphides. 

(jO Lead acetate gives black ppt ol Pb S. 

{[>) n 2 so 4 decomposes sulphides with evolution of H,S. 

Group IV. 

Not precipitated by reagents. 

1. Saturate with crystals of IV S 41 and pour carefully upon strong 

H 2 S() 4 . Brown l ; eS() 4 , N,0 2 at junction of liquids indicates 



2. Add II 2 S0 4 . Greenish-yellow gas (Cl 2 4 ), greenish-yellow solu- 

tion, and strong odor indicates II CI 3 . 

3. Concentrate by evaporation. Add K CI ; white ppt. of K CI 4 

indicates H CI 4 . 

Confirm 

1. Nitric acid. 

(a) The free acid attacks copper as in Exps. 37, 38. Heat if 

dilute. 

(b) Dry nitrates deflagrate on charcoal. 

2. Chloric acid. 

(a) H CI decomposes chlorates with evolution of CI and C1 2 4 
(mixture called euchlorine). 

(6) Ignite ; is evolved. Dissolve residue (chloride), and pre- 
cipitate Ag CI by Ag N 3 . 

(c) Color blue with indigo. Add Na 2 S 3 and H 2 S 4 , evolved 

S 2 reduces chlorate and CI bleaches indigo. 

3. Perchloric acid. 

(a) Cold H 2 S 4 does not act upon perchlorates. 

(b) Dry perchlorates evolve when heated. 

(c) Perchlorates are not reduced by S 2 (as in c above). 

DIVISION II. 

Organic acids when heated char usually with fumes and empyreu- 
matic odor. [Except acetic and some others that volatilize easily.] 
1. Tartaric acid. 

(a) Ca Cl 2 gives white ppt., soluble in acids and H 4 N C 3 ; 

insoluble in hot K H ; soluble in cold K H O. 
(6) Concentrate solution and K CI gives white crystalline ppt., 
soluble in II CI and H 4 N H O, but insoluble in H C 2 H 3 2 . 
(c) Char, characteristic odor of burnt sugar. 



CHARTS FOR ACIDS. 



173 



2. Citric acid. 

(a) Boil neutral solution with CaCl 2 ; white ppt., insoluble in 

KHO but soluble in H 4 N H O. 
(6) Add limewaterto cold neutral solution ; no ppt. Boil; ppt. 

Ca 3 2C 6 H 5 O r 
(c) Char, characteristic irritating fumes. 

3. Oxalic acid. 

[See above.] 

4. Acetic acid. 

(a) Ag N 3 in strong neutral solutions gives white crystalline 

ppt., AgC 2 H 3 2 , soluble in H 4 NHO and in hot water. 

(b) The free acid (liberated by H 2 S0 4 ) has characteristic odor. 

(c) H. 2 S 4 -f alcohol + strong solution heated gives character- 

istic and pleasant odor of acetic ether. 



Note. — The student, by original experiments upon known sub- 
stances, should extend and modify all of the above charts. For 
instance, in the " Closed- tube Analysis" it is easy to add to No. 4, 
"Change of Color, etc.," a long list. Many salts, especially carbon- 
ates, reduce to oxides of characteristic color. For example, let the 
pupil heat cobalt carbonate and note the result. 



